Our Experts

David Matthews – owner and key contributor of Carbonblack’s blog

David photo

An industrial chemist by profession, David spent 40 years in the Tyre industry. He is experienced in many aspects of tyre and retread development, technical service, testing and quality control. David spent eight years as Training Manager for Beaurepaires and Dunlop Olympic Tyres. He “tells it like it is”.

His plain, simple, technically based explanations are written so that you can understand. He will edit our blog. In his spare time, he is captain of the N.S.W. State Over 75’s Seniors tennis team; and plays a mean jazz piano.

On March 5th, he celebrates 60 years in the tyre industry- and is still keen to discuss as many aspects of the business as you could wish. He has contributed over 100 articles to our “All About Tyres” segment on practically every aspect of tyre technology.


Allan Henry

Allan Henry has spent most of his working life in the automotive tyre industry.

With more than 30 years in the industry, Allan has considerable experience in many facets of tyre design, manufacture and tyre performance.

From many years involved in tyre construction, tread pattern, and tyre mould shape design and development, tyre technical and uniformity issues related to tyre manufacture, plus road, track and laboratory testing of tyres, Allan has an extensive, in-depth knowledge of most tyre technical issues.

Allan also spent 5 years in senior technical support roles at both the tyre wholesale and retail level, making him one of very few people in Australia with real knowledge, not only of how tyres work, but also the issues facing today’s tyre consumer.

Allan is a qualified mechanical engineer, and has a Masters Degree in Management.

Blog Article from Allan: Tyre review interpretation


72 Comments Add your own

  • […] Our Experts […]

  • 2. Chris Parkes  |  November 2, 2007 at 6:26 pm

    Hi, located your web site and really interesting.

    Would like to ask your expert opinion of some Camac 195/50/R15 tyres I have that are falling apart basically.

    Tyres have done around 300 miles and the rubber is peeling off like there is no tomorrow.

    Would value your opinion and will send pictures should you wish to see these dangerous items.


    Chris Parkes

  • 3. ludocb  |  November 5, 2007 at 10:28 am

    I would have to see close up photos of the tread surface, taken at
    an angle to the (preferably) setting sun, to be able to offer an opinion (just that, an opinion) as to the cause of the abnormal wear pattern that you describe.

    Have you tried the 4 inch sellotape trick applied to a dusty surface, to see if there is an acute alignment problem. This is described in my blog, I think on “Barber pole wear“.
    I would need vehicle details, and who makes CAMAC? 195/50R15 not all that common in Australia, is it a commercial tyre or a passenger tyre. So I need more information.


    • 4. David  |  February 17, 2011 at 4:55 am

      Camac tyres were made in Portugal, and ceased production in 2008. I see in the trade press that they are just about to start up again February 20110They must have had huge problems to actually cease production.

  • 5. Denise  |  December 15, 2007 at 1:27 am

    Hi David, We have a 2006 Holden Captiva which has SP270R 235/55/18R 100H Dunlop) tyres the car has 31000. on the clock , Driving has been around town(Live in Country town) @40% and the other 60% HWYWhen we purchased the car it was pulling to the left, it was wheel allinged by bridgstone 3 times as orginised my holden dealership, It still pulled to te left after this. We decide to pay for an allingment at a Tyrepower shop who had recently opened and had new equipment, after 2 visits car was ok but still had slight pull to left. At second service of 30 thou the rear tryes were almost totaly scrubbed out, The holden dealership will not take responsabilty and neather will tyre power. My husband has since taken it to a place in Dandenong called Amberley wheel alingments and OMG the car drives like a dream. i believe that some one is in the wrong and Its not me what is your view on what I should do. Especially seing how these tryes are Sooooooo expensive

  • 6. Peter  |  January 27, 2008 at 10:36 am

    Hi Allen,

    I have a set of well worn Conti SportsContact 2 tyres on a Focus XR5 that have endured nearly 50000km. From all my reading and understanding, this is quite high mileage for a set of low profiles. I do not tend to drive hard regularly.
    The problem I am enduring is what to replace them with!
    I have been informed of a few brands worth looking at, and have read a large amount of info on different people’s opinions and I come to the conclusion that different tyres suit different cars. Obviously different tyres come with different price tags! I am after a tyre that will give great grip in dry and wet and is also hard wearing. The concept of replacing tyres at 20000km is a little daunting to me! (hence my reasons for not driving hard!) I am happy to pay the price for the right tyre.
    Would you have any advice for selecting Bridgestone RE001 Adrenalines, Yokahama Advan V103’s or another set of Conti’s for the Focus XR5?
    Thanks very much,


  • 7. David  |  February 14, 2008 at 8:30 am

    Response to the posting about 30000 km on the tyres on a Holden Captiva.

    The Captiva is an interesting vehicle. It is predominently FWD, but a proportion can be directed to the rear wheels on demand, up to 60 front/40 rear, or 50/50, depending on who you talk to. The Toyota RAV4 is the same. To have the rear wheels wear out first on what is predominently a FWD vehicle, is extremely unusual. After all, mostly they just hold up the corners.
    The front wheels drive, brake, and steer. Hard work, so they generally wear out first. The clue I read into this is that the vehicle pulled to the left since new.

    Before going any further, I would read “All About Tyres” on our website, in particular the article on “Barber Pole Wear”. A new posting due this week on “Shipping Pressures” on my blog may also prove helpful (“keep an eye on the blog”).

    You do not state whether the (many) alignments that were done were front wheel alignments only, or a full 4 wheel alignment to the thrust line. It would be possible to compensate for the pull to the left by aligning the front wheels only, without fixing the fundamental cause. Front wheel drive vehicles are very sensitive to being built, or tracking out of square. Much more so than rear wheel drive.
    The joke was that the old Holden Kingswood would take anything in the way of misalignment. Nethertheless, the Captiva is built by Daewoo in Korea, is sold widely worldwide, and it’s therefore doubtful that the original jigs on which it is built are out of square.

    By comparision, it is well known that particular runs of certain quite popular vehicles have in fact been built misaligned. So:- was it damaged or bent at the multi-link rear suspension during shipping is question 1, and did you have a full four wheel alignment done at any stage? is question 2. I assume that the tyres were rotated front to rear at some stage. (That would be question 3)(You pay extra for a full 4 wheel alignment)

    With the answers to those questions, I can only recommend that you take the matter up with the Consumer division of GMH, the address for which will be found in the vehicle handbook.


  • 8. ludocb  |  February 14, 2008 at 8:42 am

    Reply to Pete regarding his Ford Focus for posting on the blog.

    Pete, you are chasing nirvana!. To have maximum wear wet and dry with the current range of polymers and compounds is not achievable. You have to compromise!

    Tyre manufacturers undergo a long selection process to achieve original equipment fitment to a new model motor. Most drivers enjoy the choice of low profile tyres and a sportier version of the “cooking model’ by either going faster, or more likely, cornering faster. Tyres wear up to eight times faster going round corners and roundabouts, you know.

    Reading your request, if you have got 50000 km from your tyres, ( I suggest that you rotated them front to rear at some stage) I would be inclined to stay with the brand that gave you that performance, which ain’t real bad at all, in my experience.

    Hope this helps!


  • 9. Rob  |  February 15, 2008 at 12:01 am

    David or Allen

    this is a bit out of left field, but can either of you tell me what the maximum speed rating for an aircraft tyre would be? We are having a wonderful argument on http://www.recreationalflying.com.au/forum/index.php about theoretical scenarios and one person seems to be suggesting 1000 knots is safe. I think most tyres would be lucky to survive 200 knots. PS David I also like listening to jazz and particularly great players like Keith Jarrett.

    regards Rob

  • 10. David Matthews  |  February 17, 2008 at 1:21 am

    I expand a bit on aircraft tyres on our carbonblack.com.au site in “All about Tyres”. “Tyres QandA” in “How many times does a tyre go round” and “Why the difference”. I will also be posting a more detailed report on the type of qualifying testing that a jet aircraft tyre undergoes for a new “type” of aircraft (so keep an eye on the blog). In other words, the tyre’s endurance is matched to the aircraft’s performance. There is also a “high Speed Test”, again matched to the aircraft, which from memory ranges 230-250 knots.

  • 11. ANURAG MITTAL  |  February 19, 2008 at 11:44 am

    i wanted to ask why the auto tyres are shaped so.!!……..mns why they have flat bases with very slight curavture at ends..??…why has’nt there been any modification in its shape since ages??

  • 12. Our Experts on: Aircraft Tyres « The Tyre Blog  |  February 20, 2008 at 4:00 am

    […] on CarbonBlack, occasionally something comes along that piques our interest. In this case it was a question posted to our tyre expert David Matthews on aircraft tyres. Here’s David’s […]

  • 13. David Matthews  |  February 22, 2008 at 10:46 pm

    Tyres revolve, and evolve, but the shape under load fundamentally remains the same. Why is it so? Over the past twenty years or so, once radials became the standard passenger tyre, the rim diameter has increased from 13 inches to 19, the width from 185 mm to around 235. This has lengthened the footprint though I admit it is still broadly speaking, elliptical. It’s the footprint that distorts, and in so doing, does all the work of steering, cornering, accelerating, braking. If It had the contact area of say, a railway wheel, you wouldn’t be able to do any of those! And if it were laid down like a tank track, a rectangular footprint, you wouldn’t be able to go as fast due to mechanical limitations of this system (which is used on agricultural tractors by the way). Magnetic levitation seems the way to go! That would solve all those problems, just create new ones.

  • […] Our Experts […]

  • 15. Lawrie  |  October 5, 2008 at 10:07 am

    I own a Honda Accord VTi 2008. The wheels and tyres supplied
    17.75J, 225/50R17 94V. Live in NSW.
    I would like to get lower profile tyres and new wheels.
    I dream of 19/8.5 and 235/35/ZR19 but everytime I seek advice the answer comes back different.
    I seek Alan’s advice because he is not trying to push any particular wheel or tyre.
    So help me with guidelines for choosing a set of wheels (I have no idea if offset has to be considered in my case) and if there are a few tyres that would do the job, tell me guidelines so that I could make the final choice, (which most likely will be driven by cost)

    Thank you….Loz.

  • 16. Lawrie  |  October 5, 2008 at 12:04 pm

    I meant to refer to this number in my blog above.
    standard combo 225/50-17 and my choice 235/35-19.
    In the “choose Tyre” these are the results. My tyre brand was Sumitoro HRT Z II.

    225/50-17 112 mm 328 mm 657 mm 2063 mm 485 0.0%
    235/35-19 82 mm 324 mm 647 mm 2033 mm 492 -1.5%

    Does this fall within acceptable for retaining car warranty, RTA approval and Insurance companies?

  • 17. Graham Smith  |  October 13, 2008 at 2:23 pm

    I have had some Hankook Dynapro AT-A RF09 195 /80 R15 94S
    put on to my Freelander by the garage I bought the car from.
    Have you any Idea if they are any good,and if they are trully all terrain. Thanks

  • 18. Steve  |  October 29, 2008 at 9:08 pm

    Hi folks,

    I drive a 2007 Subaru Impreza RX (5 sp, manual hatch). The factory tyres are Yokohama A-spec (205/55/16). Does the job nicely when driven sedately (currently done just over 8000kms). Previously I was driving a 2002 Corolla (4sp auto sedan) and I had aftermarket Bridgestone G III on them – I loved the Bridgestones.

    My driving style is considerate and not a risk-taker. However I do enjoy the knowledge of driving on good rubber. The Bridgestone Adrenalin RE001 seems a bit of overkill for the Subaru.

    I’ve looked at the Dunlop SP Sport 3000A and Yokohama AS01 and remain undecided.

    Can you make suggestions for a decent ftermarket upgrade?

    Many thanks,

  • 19. ludocb  |  October 30, 2008 at 11:10 am


    The proposed fitment of 235/35ZR19 as a replacement is a legal fitment in N.S.W., as the match is suitable for diameter, speed rating, and load carrying capacity. Diameter changes are restricted to Plus/minus 15 mm. Track width increase also restricted to plus 25 mm.

    So when you finally decide on a fitment, check first with your insurance company, and hope that you talk to the right person there who knows what you are about.

    The section width of your current tyre on a 7 ½ inch rim is 238. Tyre tables show it as 233, but this is as measured on a 7 inch rim.

    The 235/35 measures 241 on an 8 ½ inch rim.

    As a rule of thumb, each extra inch of rim width adds 10 mm to the section width. If the rim offset is the same, then this extra 10 mm is split evenly inboard and outboard.

    However, most front wheel drive cars have a high offset outboard, so you would have to check first that a 19 inch rim with the same offset as your existing rim is available from a wheel supplier with the Honda Stud Pattern and pitch circle diameter. Most 19 inch rims on the Australian market are for the big six/V8 rear wheel drive performance cars, so this may be difficult, as they may not have enough offset. But before you do that, check whether an extra 3 mm inboard (maximum I suggest) is significant in fouling any suspension or brake components on full lock, and full jounce. So at this stage you haven’t spent any money!

    Nethertheless, I think that you are on the right track. If you would like further reading, our “All About Tyres” on “Rules of Thumb- Lower, Fatter, Wider”; “Extending Track Width”; and “Reading a Tyres Message” will provide background information.

    However, when you use the Carbonblack Tyre Exchange facility, and invite bids from performance tyre shops in your area for the complete package deal, it may prove cheaper than buying the individual components, including wheel nuts suitable for the new wheels, and a lot more convenient!


  • 20. ludocb  |  October 30, 2008 at 11:12 am


    The AT in the tyre type description stands for “All Terrain’, and if that’s what you were looking for, one with good on and off-road capability, that is what the manufacturer is claiming for their tyre.

    However, one thing you should know about. I assume that yours is a 1998 Freelander, the original equipment for which was 195/80R15 91T. The 91 T stands for the load it can carry at a certain speed and pressure. T is a higher category than “S” which you have now fitted (190 km/h as compared to 180 km/h). So you say, the old girl will never do that speed, so what does it matter. Answer- it matters if you haven’t advised your insurance company, and got their approval, best in writing. Mostly, if you tell them that the original equipment tyres are no longer available, or far too costly, the insurance company will probably agree to continue to cover you.


  • 21. ludocb  |  October 30, 2008 at 11:19 am


    205/55R16 is a size that I have had quite a bit of experience with, on my Nissan 200SX cars- two over the years.

    The original Yoko 008 assymetric tyres were great, suffered in the wet a bit, but gave good wear because they had more rubber on the road- one solid bar on the outside.
    The next 200SX had Bridgestone, I seem to remember, and these did 35000 km, the Yokos (on a different model, but substantially the same), had done 50000.

    So I put on the Dunlop 3000 -, the pattern has a high void ratio to tread rubber, and the wear should them out at about 25000. This may be because it has silica in the tread rubber replacing some of the carbon black to improve wet grip – the selling point for this tyre.

    However for your style of driving in an Impreza, I’d be inclined to suggest Yokohama, the more rubber on the road the better, bearing in mind it’s a trade between wet grip and tread wear overall.


  • 22. Bob Moore  |  December 31, 2008 at 8:46 am

    Have tyres on XR5 turbo (Continental sport 2) and after having only driven 20,000kms have bee n advised that tyre needs replacing as it has come away from wheel wall, question would I have a claim as have only driven easy highway kilometers and with little wear and tear. thanks in advance Vob

    • 23. ludocb  |  January 7, 2009 at 6:36 am

      A Claim Tyre
      So you reckon you’ve been sold a “bodgy” tyre- and you want to seek redress for it. The tyre just didn’t perform, or developed a fault which.
      In tyre speak it’s known as a “claim tyre”.

      Consider the following – all products sold on the Australian market are guaranteed to be of marketable quality under Consumer Protection laws. So if the tyre has failed in service due to defects in quality, materials, design or manufacture, then it should be replaced by the manufacturer. Experience shows that these types of defects show up early in the tyre’s life. So generally speaking, there’s no hassle in getting it replaced, though the paperwork involved gives the processing dealer a pain. Think of it as actually doing the manufacturer a favour, because if the design or manufacturing process is suspect, then the earlier it is fixed the better.

      The amount of the “claim” is generally determined by the amount of level of tread life remaining- though it might be slightly skewed in favour of the customer if it happens very early as the inconvenience factor to the customer comes into play. This is a policy matter for the manufacturer to deal with.

      A Damaged Tyre
      Consider, though, also the following. Tyres operate in a very harsh environment, called the Australian road system. They must be suited to the service application, in which they are to be used. The tyre must also be suited to the application. If a particular type of tyre repeatedly fails in a service application, it probably needs to be up-graded to a superior tyre. In Australia, heat, long distance driving, and heavy loads are the major factors affecting tyre life. If this is your normal driving routine, then an upgraded tyre in either load bearing capacity (the number figure e.g. 96) or the speed index (S.H.V.Z. etc) will give the tyre more reserve capacity to cope with the conditions. Just get your mind around the fact that “heat” is the enemy of tyres, and the speed. Load, and distance are all important in determining satisfactory service.

      Finally they must have adequate reserves of performance to cope with every day abuse, which is covered by the Australian Design Rules governing tyres fitted to new cars.
      The environment can cover factors as diverse as broken road edges, potholes, broken timber bridge decking, off-road protruding sharp rocks, tree roots – the possibilities for damage are endless.

      Damage can result in cuts into the tread area, which admit water into the under-tread and steel belt area. The belts rust, lose adhesion to the rubber, and a separation of belt to tread occurs.

      Sidewall damage can cause fractures inside the tyre casing in the sidewall area, which fracture the reinforcing cords there. The unsupported casing flexes excessively in that area and either it cracks through to the inside of the casing, causing a bubble, or right through, which causes a rapid deflation.
      So if you suspect that the sidewall has been damaged (a bent rim is a good indicator), the tyre must be stripped from the rim, the beads spread, and the tyre examined closely from the inside.

      Road Hazard Warranty

      Damaged tyres are not “claim” tyres- it is damage incurred during service. You can insure against the loss of the tyre by taking out a “Road Hazard Warranty” at the point of sale. Most tyre dealers offer this service.

      When you lodge claim on the tyre maker, these figures are collated, and if the numbers get too high, then either a recall can be instituted, (voluntarily or enforced) or more commonly, a design modification is made to upgrade the tyre’s performance.

      Tyre design engineers believe fervently that the customer can dream up more ways of using and abusing a tyre than they ever could!

  • 24. ten alley  |  February 6, 2009 at 5:41 am

    found it hard to find a good tyre for 205/65/r15 for vienta.
    went to yellow pages and could not compare tyres.
    found carbon black useful in getting a shortlist of 6.
    picked dunlop sp sports 300e and still not sure which one is best.
    would be good if manufacturer tyres are rated in numbers and the table can be sorted in price as well as ratings.
    comparing 6 tyres would be useful if more info given which clearly allows us to choose the best.or if your system arranges them in rank order with reason clearly.
    thank you

  • 25. Kelly  |  February 7, 2009 at 11:49 am

    Hi David & Allan

    I have a boat trailer with 9″ Olympic brand tyres, the only markings are… “Olympic Trailer”, “6.00-9 Ply Rating 4” & “Made in Australia Reg No 38526”

    I’m re-registering the trailer and need to be able to demonstrate that the loading bearing rating of the tyres is sufficient for the weight of the boat. The rims are 512kg, but the tyres have no weight markings.

    The tyres are in good order, so I don’t want to have to replace them unnecessarily. Do you know of any catalogue with the weight bearing spec for these tyres?


  • 26. ludocb  |  February 9, 2009 at 11:25 pm

    Dear Kelly,

    600-9 4 ply rating tyres can carry a load of 400 kg at a maximum pressure of 275 kPa (40 p.s.i.). These are a small, high pressure tyre for trailers such as boat trailers.


  • 27. Josh Moss  |  March 1, 2009 at 3:02 am

    The original set of tyres fitted to my Land Cruiser gave me 80,000km of wear. But the 2nd set are looking far more worn than I think they should, even though they have been balanced and alternated. This set has done only approx. 60,000km. Sound this sound correct?

    Factory pressures say 32psi but I’ve always run them at 36psi. Some drivers have told me that 40psi give better ware.

    • 28. David Matthews  |  June 14, 2009 at 1:56 am

      I have to assume that these were the same brand tyres, and pattern, in which case your Landcruiser has now done 140000 km, and a third set ot tyres is contemplated. Land Cruisers can be fitted wirh everything from a 7.50R16 light truck tyre to a low profile R.V. tyre of 275/60 profile, or even lower. So I have to generalise in my answer.

      Wear of the steering and suspension components, changed driving habits or route, different terrain, the propensity of councils to build more roundabouts,and re-surfaced roads can all change tread mileages, as can loads, pressures, towing a trailer or van, and importantly, temperatures.

      As your tyres are in all probability radials, the change to tread wear due to pressure variations are minimal; a little more or less body roll might be noticed, with consequent shoulder wear, (which your rotations may have hidden) but that’s about it. Pressure changes lengthen the tyre footprint (lower), or stiffen the sidewalls (higher), but don’t change the crown radius of the tyre on the road- the steel belts hold it to the design shape.

  • 29. andrew  |  March 10, 2009 at 7:35 pm

    hi, i have on my car 205/55-r15-82v can i put on 195/50-r15 on to my rims instead cos i have had some given? many thanks.

    • 30. ludocb  |  March 11, 2009 at 6:45 am

      Hi Andrew,

      Please see our tyre sizing calculator Tyre Sizing Guide

      Specifications Sidewall Radius Diameter Circumference Rev/Miles Difference
      205/55-15 113 mm 303 mm 606 mm 1905 mm 525 0.0%
      195/50-15 98 mm 288 mm 576 mm 1810 mm 552 -5.0%

      More on this for your interest: https://tyres.wordpress.com/2006/12/05/benefits-of-larger-diameter-rims/

      But more on your specific question…

      The 195/50R15 are 82V, and normally 205/55R15 are 88V. So you may wish to check your tyre sizes. If in fact your vehicle placard requires an 88V, then the 195/50R15 will not be legal.

      See the state by state regulations.

      As for the greater picture as to where it fits, it’s incorporated in the tyre sizing calculator.

      Most states permit a plus or minus 15 mm tolerance on diameter, so the tyres are too small in diameter to be legal. However, if the Service index situation is O.K. then the insurance company may permit them as a fitment. The rim width, although not stated, could be O.K. It’s probably six inches.


  • 31. Dave Pledger  |  March 12, 2009 at 1:43 am

    David and Allan

    I am competing in Targa Newfoundland in a 59 mini cooper. We are running Yokohama 165/70/10 A032R tires. A new rule is being contemplated that would require tires to have a tread wear rating. Those that do not will be subject to a stiff time penalty which would essentially make us noncompetetive. Because we have small engines we really need to be able to outhandle the big cars – they use grunt for compete, we use grip. Oddly, Yokohama does not have a tread wear rating for these tires and this has created a unique problem.

    There are very few tires available for 10 inch wheels that are competitive.

    I am trying to find an approach to this impending rule – specifically to try and quantitate a wear rating for the yokohama when none is specified. Any ideas ? Do you know where I could go to obtain this info ? So far I have nothing

    Dave Pledger

    • 32. David Matthews  |  June 14, 2009 at 1:38 am

      Sorry about the late reply, which ran up a lane in our system. I hope that you are enjoying your rally season.

      The Mini came out in the sixties with first 5.20-10 cross ply tyres, then very quickly to 145R10 textile belted Pirelli Cinturato and Dunlop SP41 tyres. These have all now passed into history, and the only 10 inch manufactured now that I know of is the tyre you are on. You could try the Pirelli catalogue though.
      Further information on the Uniform Tyre Quality Grading System will be found in our “All About tyres’ on our carbonblack.com.au website. The system was introduced in the sixties by the U.S.A. Department of Transportation. Because of the expense, basically if the car wasn’t sold in America manufacturers didn’t bother to qualify their tyres, size by size, thru’ the American system. That’s why your tyres of that vintage don’t carry the U.T.Q.G code. Reading between the lines, i would say that the controlling body of the Targa is trying to hog-tie you so that you can’t use racing slicks or really gummy tyres. There were at one time tyres for studded use on ice, used in the famous Monte Carlo rally, which the Mini won (Paddy Hopkirk as I recall).

      However, in Australia, the Mini had derivatives called the Bushman, the Mini-Moke, and the Californian. All had 13 inch wheels, and associated mechanicals .The Morris 1100 had 12 inch wheels, was slightly bigger than the Mini. You might be able to locate these through the Mini clubs in Australia; use would of course be dependent on scrutineering rules for you. However, you would have a much better chance of picking up suitable 13 inch rally/racing tyres than 10 inch in Canada, I would think. Hope this helps. David.

  • 33. Paul Chu  |  March 18, 2009 at 4:30 am

    My tyres are BFGoodrich 20555ZR16 (90) G-Force Sport. Is the ZR in the description the speed rating for over 240 kph? The tyre also has the product label BF2055516GFSV. Is the V in this label the speed rating as well?

    These tyres are made in Thailand. Does the country of manufacture affect the quality?

    Thanks for your advice.

    • 34. ludocb  |  March 26, 2009 at 1:02 am


      Probably GFSV is the pattern description. The ZR is the speed rating. Without a further Service Index (Load Index and Speed Category combined) at the end of the size branding, a ZR rated tyre can carry 100% of its specified load at speeds to 240 km/h. Above that, higher speeds are permitted provided that the loads are reduced. This greater speed range is agreed between the vehicle maker and the tyre manufacturer. The only source for this information would most probably be the car handbook. (We are talking Ferraris and Lamborgini type cars here.)


  • 35. Sal  |  April 1, 2009 at 7:28 am

    Our Renault megabe needs new tyres. Currently we have Continental Contact 2, but they will be $200 more per tyre compared to the Michelin Precede PP2. Will the Michelin be as good for performance, grip and cornering?

  • 36. Steve Abigail  |  May 6, 2009 at 7:33 am

    HI, just looking to get new tyres for my 86 Porsche 928S….225/50 R16 92V it has Faulkens on it when I bought it……not that impressed. I have been told Pirelli P7’s are good…..can you help me in this direction? regards Steve

    • 37. David Matthews  |  August 5, 2009 at 8:01 am

      Yes I just put 205/55R16 Pirelli P7’s on my Nissan 200SX. I’m quite impressed. They are an asymmetric tread pattern, so a little bit of fast cornering shouldn’t disturb them too much They are also remarkably quiet I find. Possibly not fully up to the mark in steering response, but I feel that you would have to pay a lot more for Pirelli’s further up the totem pole to markedly improve this aspect.e.g. P Zero’s.

  • 38. Raj  |  June 22, 2009 at 11:24 am

    Hi David,

    I am planing to upgarde my Hyundai Getz tyres from 185/60/R-13 hankook to 195/50/R-14 Hankook R-S2. Now after working on this since last 2 weeks, i am still confused to buy hankook R-S2 or Michilin sports series. I would request you to please guide me to buy the right tyre for my machine.

    Many Thanks

  • 39. Kelly  |  August 9, 2009 at 11:11 am


    I’m needing to buy some 225/50R16 for my Holden commodore.

    I will be driving in QLD (which as we know can be wet) so wet handling is very important. I have read bad reviews on bridgestone / goodyear / dunlops regarding amount of km’s before they wear out. Am looking at Maxxis MA V1 which reviews say are good wearing and handle well in the wet – but can you believe the reviews???

    Any ideas would be much appreciated

  • 40. Rendell Day  |  August 23, 2009 at 4:21 pm

    I have problems with foam filled earth moving tyres. The lock rings come loose and the rim separates from the tyre. Have you any advice what the problem could be. Tyre sizes are 1400 x 24.

    • 41. David Matthews.  |  October 8, 2009 at 10:01 am

      There is not enough sideways (lateral) pressure on the sidewalls to keep the tyre beads fully engaged (shoved) up the bead ledge to keep the beads seated. Once the beads of the tyre are dislodged into the wheel well, the lock ring comes loose,and then starts to chew into the tyre. Foam filled tyres (or so called solid, partly flexible) polyurethane filled tyres are generally only used for very slowspeed operations in highly puncture prone operations, such as rubbish tips and the like. Higher speeds will cause problems such as you describe, the heat degrades the polyurethane, and the problems begin I hate to say this, as a 55 year tyre man, but the solution may be to go to a vehicle with tracks, like an army tank, only rubber tracks..

  • 42. Lawrence  |  September 18, 2009 at 1:52 am

    To whom it may concern,

    I have just bought a 2007 Holden Commodore SV6 VE with 18 inch alloy wheels on them and need some advice as to the recommended set of tyres I should get.

    The current set of tyres are as follows:

    Back – Runaway – 245/45 ZR18 100W
    Front – Bridgestone Potenza – 245/45 R18 96V

    Yours sincerely,


  • 43. Carol  |  September 19, 2009 at 9:22 pm

    Hi Everyone
    I want to buy some white swan car tyres for the garden.
    Yes I know I’m mad! Any idea where I can get some?

  • 44. Lesley Matthews  |  October 15, 2009 at 3:25 am

    I need some advice. I am up for 4 new tyres for my 100 series Landcruiser. Last time just opted for the tyres from factory- Grand Trek and have had no issues got 60,000 km out of both sets. Have been told there are now better tyres in the market. I am looking at either BFGoodrich Long trail or Michellin Latitude cross. Only use my car for long trips to the snow and around town. Which tyres would you say is the better for snow and mileage?

  • 45. David Matthews.  |  October 27, 2009 at 4:59 am

    A very sharp knife (box cutter) is great, a little bit of water to lubricate the knife, and a lot of inspiration will do the trick. Then use white “plastic” paint, not enamel to cover the black. Don’t be surprised if it turns light brown after a while- that’s the chemicals in the rubber designed to protect it from sunlight. Just paint it again. David

  • 46. Gary Hartmann  |  November 21, 2009 at 1:10 pm

    Hi David,
    I have a bit of a story to tell. I stumbled upon your articles when searching for an Olympic Tyres logo for a trivia competition I’m organising for work. Olympic Tyres has a special place in my heart(through dad). Whilst my memory of you is a little different to your photo, my early memory of you was christening dad’s boat at St Leonards by catching the first whiting a long long time ago(just beating myself by the way). Anyway, couldn’t help but to send a mesage to say I hope you and your family are going well. The old man had nothing but great things to say about you and I hope the fish are biting. All the best, Gary.
    Happy to converse via email !!!

  • 47. Jorge  |  December 11, 2009 at 3:27 am

    Tires dimension

    I am driving a Huyndai Sonata Limited edition. I am using tires: P215/55R17
    I want to buy a snow tires and rims.
    Do I must buy the same Widht=215, Aspect ratio=55 and the same Diameter=17
    What are the options that I have if I want to change the dimension of the tires?

    Thank you


    • 48. David Matthews  |  January 19, 2010 at 5:53 am

      There are three considerations:- The law that applies in your jurisdiction, your insurance company, and the availability of suitable rims and tyres to suit your vehicle. I assume that, since you are considering snow tyres at this time of the year, that you are in the northern hemisphere.
      These wheels and tyres will then be removed for summer

      Use our tyre calculator to match the dimensions of your exisitng tyres,but be aware that snow tyres will most probably have a deeper tread pattern, and so be slightly bigger in diameter, so check your clearances (steering linkages, mudguards, full lock) first. However, I imagine that you also would prefer to fit a wider tyre, so you should look at what is available in rims and tyres in 18 inch diameter. The tyres would have to be of lower profile if you increased rim diameter. Our tyre calculator will help in this, but eventually you will have to consult a tyre/wheel supplier to get the best package..

  • 49. Alastair  |  January 12, 2010 at 11:43 pm

    I have a boat trailer with Olympic Trailer tyres similar to Kelly in a previous request who had 9 inch tyres, mine are 8 inch.
    The tyres are 4.00 – 8, 4 ply.
    What would the load rating be for these tyres?
    The trailer was built in 1985, 25 years old, do tyres deteriate over time?

    • 50. David Matthews  |  January 19, 2010 at 5:38 am

      Tyres do last a long time, don’t they!.
      Your trailer tyres in highway service will carry 265 kg each at an astonishing pressure of 60 p.s.i. (425 kPa), which is the maximum permitted for a 4 ply rating tyre.
      The smaller the tyre volume, the higher the pressure required to carry the load. Think also about the fact that the rims are 25 years old too! Hope that they are neither fatigued or rusty.

      For information, these small high pressure tyres can carry:-180 kg at 32 p.s.i; 215 kg at 44 p.s.i.;265 at 60 p.s.i.. Yes, tyres do deteriorate over time, but the deterioration is usually due to excessive sunlight crazing the walls, or flex cracks where the tyres have been standing in the one spot for a long time.

      You’ll find several articles in “All About Tyres” on tyre storage, and attempts by legislators to impose lifetime limits on tyres.

  • 51. B.Grant  |  March 11, 2010 at 12:05 am

    We know that tyre temperature increase causes pressure increase however what exactly is the chemical or physical process process that causes the pressure rise? Is the pressure rise caused by the moisture content in the tyre? Is it correct physically and chemically that dry air or nitrogen should not expand due to temperature rise?

    For example, for a number of years we have been replacing compressed air (pumped into the the tyre by an air compressor) in race tyres with nitrogen. We use a purging process where we evacuate the tyre using an evacuation pump a number of times and then refill the tyre with nitrogen. At each step in the process we measure the moisture content of the tyre. We continue with that process untill there is no disearnable moisture in the tyre at all (0.1%).
    The car will go out on the track, do it’s laps, generate heat and when it pits we measure the pressure. There will be a pressure rise and also there is moisture content increase to 10 to 15 %.
    So where has the moisture come from?

  • 52. David Matthews  |  March 11, 2010 at 10:01 am

    Wow! That’s quite a question. I’ll do my best to answer it.
    The temperature increase is due to the energy “lost” ( you can never lose energy) rather transformed when the tyre is flexed. Although rubber is the most perfectly elastic of all substances, energy input ( from the petrol tank) is not fully recovered, being transformed into heat. This is known as the “hysteresis loop”. Some of the heat is radiated to the outside of the tyre and rim, some is captured in the rubber, being highest generally at the thickest part of the tyre (it can’t escape because rubber is a good insulator), or it heats up the gas inside the tyre, which as a result, expands if it could, can’t, so increases the pressure because it’s confined. All gases obey the “gas laws”- and here you have to go to high school physics and look up “Boyles Law’ and “Charles Law”. The third consideration is as you have found, the moisture content. The total pressure in the tyre is the sum of the partial pressures, and one gram of water makes an (astonishing) 1700 milliters ( cubic centimetres) of steam at one atmosphere pressure, from memory, at its boiling point. B.P. increases with pressure.
    So the internal pressure of a tyre filled with dry air, or dry nitrogen, increases with temperature, and increases MORE with moist air. Air is 80% nitrogen, 20% oxygen in round figures, ignoring all the minor gases such as CO2, ozone, etc, but it always contains some moisture as well. Here we digress into relative humidity. which is a measure of how much water vapour air can hold without it condensing into liquid water. Air at 30 degrees holds a lot more water without it condensing that at 10 degrees- something like 90 times more with each at 100% relative humidity.
    So if you want to control ( minimise) your pressure rise in a tyre use either “dry air” or “dry nitrogen” the latter being freely available, because it’s a by-product of making liquid oxygen for welding purposes. Or use air from a compressor fitted with an efficient aftercooler.
    The highest pressure rise will be in the tyre under the most stress, ( the hottest) which is what you are interested in. Dry air eliminates a variable from the equation. The moisture content inside is the same as when you measured it after purging and filling. It doesn’t make water inside the tyre, believe me. It may well be that originally there was some liquid water in the tyre, which transforms into “steam” ( I admit unlikely), or that the moisture content measuring device has to have its air stream at the same temperature as the original readings to make a valid comparison. You could test this by bottling a sample, and letting it cool down.

    • 53. B.Grant  |  March 15, 2010 at 6:02 am

      thanks for the reply. I should explain that we do measure the moisture content during the whole process of purgng.
      We only use bottled nitrogen to fill and purge the tyres. No atmospheric air gets into the tyre during the purge process. The system is completely sealed so when we evacuate the contents and refill it each time only fresh, uncontaminated nitrogen enters. The nitrogen(and it’s water content), which is sucked out of the tyre during the purging process, is expelled .We check the moisure content at each purge and we continue the process until no moisture is present.

      However, and I understand it’s hard to believe, when we measure the moisture content of the tyre after it has been run…….there is a huge moitsure content increase.

      That is the issue, a tyre goes out registering minimal moisture on the gauge and comes in with an amazing increase reading on the same gauge. How did it occur?

  • 54. David Matthews  |  March 17, 2010 at 9:51 am

    You said it. The system is sealed. So it must be in the manner in which the moisture content is measured. I would purge a pressure proof container (not a tyre),e.g. a compressor tank and then warm it up to the temperatures encountered by your tyres, and measure the moisture content before and after heating, and also at the same final temperature after heating, to see if you can reproduce that which you describe.
    Tyres are moulded at 170-180 degrees Celsius. They may sit in a tyre store for months, but any moisture absorption would be minimal. Wasn’t always the case. Rayon carcass radial tyres absorbed moisture, up to about 12% moisture in the rayon, from memory, over a long period of time or thru’ puncture holes. Nylon and polyester used today,don’t to any extent. High moisture content would cause the tyre to delaminate, because the cords lose their bond strength to the rubber compound in which they are buried. This used to happen when rayon tyres were retreaded, because of the high temperatures used to remould them, similar to new tyres. Cord used in new tyres is bone dry, and encased in rubber.
    It’s an interesting problem you pose, and perhaps you could throw some light on it by carrying out the test I suggest. I’d be interested to know the result.

    • 55. B.Grant  |  March 18, 2010 at 8:06 am

      I will organise to do the test and let you know and thanks again for your ideas and input.

  • 56. David Matthews  |  March 26, 2010 at 9:19 am

    Been thinking about this further. The gas in the bottle is under high pressure. When it is used to fill the tyre to say 40 p.s.i., it expands. This cools it down. When this cold gas is expelled to purge the tyre interior of residual air soon after, it expands, (40 p.s.i. to atmospheric) and cools down again (I think). So the tyre itself gets progressively colder ( I think!), and the exhaust gas similarly.
    If you are using a hygrometer to measure the moisture content, then you are measuring relative humidity ( see first answer), which is temperature dependent.
    I had a look at nitrogen filling at our local Jax tyre service.Unless the air is bled out progressively as the tyre is filled with nitrogen, then it is indeed difficult to get all the air out and replaced by nitrogen, which is not how they do it. Yet they would if it was an LPG bottle, not a tyre.
    So I would be very interested to know the temperature of the exhausted air or nitrogen at each stage of the process as outlined in the second reply I made.
    P.S. I still haven’t a clue as to where the ( alleged) moisture comes from. What do you use to measure moisture content?

    • 57. B.Grant  |  April 3, 2010 at 12:06 am

      the device we have for measuring moisture content is a small hand held hygrometer gauge with a tyre valve fitting attached to allow measurement of the tyre contents directly through the shreader valve. All I know is that the unit is from an american company and is brought here by a tyre guy who works for one of the V8 teams. He won’t say where it’s from and there are no markings on it to indicate manufacturer.

      I have all our instruments scientifically calibrated regularly so that we have accurate reliable data and the unit, although not calibratable has been passed.

      Your right in that we can’t possibly remove all the air from the tyre however that is why we use a vacuum pump which helps but there is a small percentage of air still remaining obviously. We vacuum the tyre down three or four times. Each time refilling it with fresh bottled nitrogen. As I have said previously, it is a sealed system so each to time we vacuum down the tyre only pure nitrogen is introduced.

      We have also fitted internal tyre temperature and pressure monitors however I haven’t been able to test accuracy of the temperature data yet to comment on that with confidence.

      I might have to look at the availablity of an external tyre air temperature gauge

      I haven’t been able to perform the test you suggested yet however I hope to do so shortly

      • 58. David  |  November 23, 2010 at 4:46 am

        I note that P.C.L., a company in the U.K., has just commercialised a unique tyre inflator that purges the nitrogen as the tyre inflates. This might solve part of your problem.

      • 59. David  |  February 15, 2011 at 4:39 am

        Snap on Equipment has also released their N2 Nitrogen inflator under the Hofmann and John Bean brands, in the U.K. They’ll pop up here eventually!

  • 60. tyres in redditch  |  June 13, 2010 at 4:10 pm

    Nitrogen in tires is becoming a popular replacement for standard air.When it comes to tire inflation,nitrogen has many advantages over oxygen.That is,a lot of articles i read about it and really impressed me to its advantages.

  • 61. Faye  |  July 7, 2010 at 5:48 am

    I have just had my 2008 hyundai sonata in for 15,000 service and it was found the inner side of the rear tyres had scrubbed out. Hyundai say this is not their problem. What could cause this? The car is rarely driven on open roads and always driven with care (no bikkies). The front tyres still look like new. I hope you can help me know what to do.

  • 62. Ming Loi  |  July 9, 2010 at 7:39 am

    Dear David,

    How are you? We produce obitreat & precure linear for tyres retreader in Malaysian truck. Currently, we are looking for importers or partner to tie-up and expand this busines in Australia.
    We had few call with retreading companies.

    What is the potential in Australia? What steps to avoid?

    Thank you in advance.
    Ming Loi

  • 63. David Matthews  |  July 9, 2010 at 9:06 am

    Go to our “Tyre Blog by E-Mail ” segment. Look at items 11, my answer 12, and my answer 15. If the problem is similar to what is described, ( only in this case at the other end of the vehicle), then look up “Shipping Pressures” my article, which will give you the clue that your car has had its rear wheel alignment upset when the car was being shipped. It will re-inforce your feeling that there is something wrong- either with the tyres being built off centre, or the car’s rear wheel linkages/suspension has been bent. You are quite right- 15000 km on the rear tyres of a front wheel drive car indicates that something is very wrong. Beware the “flick pass”. Ask for a full four wheel alignment to the thrust line (at their cost). If this is O.K., then it must be the tyres

  • 64. Jessica  |  August 28, 2010 at 11:04 pm

    I have a ’97 Hyundai Sonata. The tires call for a 195/70 R14, I was short for the price, so I got 165/70 R14. Is this okay to do or will there be severe consequences? Thank you very much.

    • 65. David  |  November 6, 2010 at 12:07 am

      It all depends on whether the tyre placard on your car ( on the door pillar, driver’s side, on the glovebox lid, or on the petrol tank filler flap) permits this size. Generally, a range of tyres is permitted. If the 165/70R14 is on the list on the placard, you’re legal. If you can’t find it, consult your car handbook. If not on the list, you have in all probability voided your insurance policy, and if your car is subjected to annual inspection or periodical roadworthiness, you have voided that too. Looking at the difference (165 to 195 in section width), you are probably illegal, as it is a big step down. It also affects your speedo reading, and will require a higher inflation pressure to carry the load than specified for 195/70. The way you spell “tires” indicates that you’re from overseas.Have a look at our “Tyre Size Calculator”

  • 66. RALPH AMORE  |  October 8, 2010 at 11:52 pm


    I have a new Range Rover Sport purchased Feb 2009 with Continentals 4×4 Sport Contact 275x40R20 106Y. After 3,500 km I noticed some serious wear around the front shoulder areas of both tyres. I consulted my mechanic whom directed me to have a wheel alignment which I did but also rotated the tyres at the same time. By 8,500 km’s my mechanic pointed out again serious excessive wear. The tyre pressures are usually kept about 42-44 PSI. He suggested we rotate again. By 12,000 km’s one front tyre has had to be replaced as the metal inside the wheel rim has exposed. The other front tyre I am advised should be replaced. The back two which have been at the front have also been affected. I have contacted the dealer and he has asked me to bring the car in. They cant surely suggest I have not been on top of the problem when it first started to come up at 3,500km’s. Surely these tyres should give me at least 20,000kms. Your thoughts would be appreciated.The vehicle is city driven and is immaculate condition and garaged. Thanks.

    • 67. David  |  October 9, 2010 at 10:51 am

      The Range Rover Sport tyre equipment raised my eyebrows the first time I saw one. These are real trend setters, being a very expensive high speed low profile tyre on what is popularly regarded as an off-road vehicle, which just happens to be high powered as well.
      What you haven’t said is precisely where the wear on your tyres is occurring. I presume that it is on the inside shoulder of the tyre on the front wheels only.Usually this is due to excessive toe-in, which is an alignment problem, and occurs in the same manner on both front tyres.
      There is another alignment cause, and that can be due to the rear axle being out of alignment with the front, in which case the outside edge of one front tyre, the inside edge of the other, wears rapidly, since the vehicle crabs its way along. This can only be rectified after a full four wheel alignment to the thrust line. Dependent on the actual wear pattern, maybe this is required.
      I doubt that pressure is playing a part, though excessively low pressures could contribute due to body roll, wearing both shoulders of the tyre. In which case, the pressures on the tyre placard on the vehicle will give you the clue. Too many roundabouts, perhaps?

      • 68. David  |  January 6, 2011 at 7:02 am

        Further to your problem, I had a look at a Rangy this week. Every tyre was bald as an egg on the shoulders, both tyre shoulders. They were the 20 inch tyre, Continental, made in Hungary or somewhere like that. Looking at the vehicle, it has a high centre of mass, high roll centre. But that is probably not the problem, having had a look at the tyres. As I pointed out earlier, this is a high powered vehicle, capable of going very fast, expected to perform off road as well. These two requirements conflict. But government legislation compels that if your vehicle can do 200 km/h, then the tyres MUST be capable of it. So faced with this dilemna, the tyre design engineer has to make the primary function that the tyre perform at speed. The way they do this is by cutting the volume of rubber in the shoulder area of the tyre. What was apparent was that the worn shoulders were showing through to a different compound laid under the tread surface, so the actual design of the tyre is quite complex. So I can’t “knock” the tyres. It is quite difficult to design a heavy, high speed tyre.

  • 69. Adrian Tourle  |  November 21, 2010 at 2:49 pm

    hello David

    ive read and understand a little about tyres but have not been able to figure out if following the manufacturers recommendation would be the best solution for the vehicle and our intended use(s).

    we own a grey import – nissan elgrand 2001 apwe50 (essentially an enlarged tarago with pathfinder suspension, vq35 petrol motor -177kw), we have the 4wd variant (RWD/auto/4WD), seats 8, weighs 2120kg unladen. Recommended tyres are 215/65r15 96S.

    We plan some suspension mods. Probably1.5″-2″ lift; either longer springs & dampeners or air springs plus larger tyres – another owner has BFG AT 215/75r15 with std suspension.

    80% its used around town, Mums taxi. Even then the rear frequently hits the bump stops (the suspension needs attention). We plan to do some campervan touring – towing about 1.4t, hoping for 4-6 weeks a year, and I love dirt roads, camping & going the long way. I know this will not go where the pajero went.

    Anyway it weights say 2.2t, 7 people say 400kg, holiday gear, say another 200ish, plus tow.

    So bearing all that tyres would you suggest, Ive been recommended the BFG ATs, Continental vanco 2, Federal…

    & should we fix suspension or change tyres first?

    Can the load rating be excessive? ie sidewall too stiff, reduced flex in rubber & less traction?

    thankyou kindly in advance


    • 70. Adrian Tourle  |  November 21, 2010 at 3:00 pm

      oops, proof reader asleep “So bearing all that in mind would a wider rim & tyre (or even just larger profile tyre) improve handling and safety? & if so what wheel size, rim width, tyre size and load rating would you suggest? “

  • 71. David  |  December 6, 2010 at 9:21 am

    Your existing tyres can carry 710kg/tyre. It is recommended that they be loaded in service for not more than 85% of rated load. Your empty vehicle, assuming 50/50 weight distribution, calculates to 530 kg/tyre. Now you add in 7 people. They weight 68 kg /person, using tyre standards; total 476 kg, additional 119 kg per wheel position, brings it up to 649 kg, which is 91% of rated load. Not good engineering practice. This is assuming no drawbar load (level rides), and even weight distribution. So you have to go to a bigger tyre, either wider cross section, or higher aspect ratio. This might change your gearing ratio also, so diameter matching is preferred. I assume also that all luggage would be placed in the trailer/caravan trailing along behind. From your description, I guess 4 wheel drive would be used when towing, otherwise rear wheel tyre wear would be rapid. So jack up your suspension to allow for higher diameter tyres, or mudguard flares for wider 15 inch tyres, provided your rims will suit a wider tyre. Go for a tyre with higher speed rating than “S” to improve reliability. When I first read this, I thought “He’s off to the Queensland outback” Ultimately, you will have to get an engineer’s certificate approving of modifications to take to your insurance company, before you do anything! (In Qld, you used to have to go to the “Machinery department”. I’m not sure that this is still the case.) However, you are from Sydney, so subject to N.S.W. legislation. Consult you local R.T.A. office re permitted modifications, which limit increases in diameter to +/- 15 mm, track width increases to 25 mm. Also use our tyre matching tables located in our “All About Tyres” segment.

  • 72. michael  |  June 7, 2011 at 8:46 pm

    I own a 2007 chevy truck 1/2 ton Sierra 1500 . It has 275 x 55 x 20 tires from the factory. I would like to put 285 x 40 x 22 tires on and I am wondering if this is a bad idea. Will I loose any benefits?



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