Here’s the plug! Stuckey Tyre Service

Stuckey Tyre Service is one of Australia’s premier suppliers of car tyres, whether for vintage or motorsport application, or everyday road use. We supply all the major premium tyres. Our sales office and warehouse are located at 828 Sydney Road Brunswick, Australia.

Servicing the demands of Australia’s leading motor racing teams has provided us with unrivalled knowledge of the best performance tyre and wheel combination for every application, road or track. From the most exotic European sports car to the average family sedan, we at Stuckey Tyre Service have a carefully selected range of tyres and alloy wheels to enhance the road performance, safety and appearance of your car.

At Stuckey Tyre Service you can take advantage of the ultimate precision fitting and balancing service where the utmost care is taken with your valuable tyre and wheel purchase. In particular we take great pride in being able to balance a wide variety of specialty wheels including wire wheels for historic applications. The most advanced fitting and balancing equipment is used by skilled technicians whose work is trusted by Australia’s top race drivers at speeds over 300Kpm.

We at CarbonBlack love sending customers to the Stuckey team.

Our experts on: Uniform Tyre Quality Ratings

Apart from tyre size branding, many Australian drivers may have noticed other markings on the sidewalls of their tyres with ratings for treadwear, traction and temperature. These Uniform Tyre Quality Grading System (UTQG) ratings are based on rather outdated U.S. legislation which requires all passenger tyres sold in the U.S. to have them.

However such ratings are not a legislative requirement anywhere in Australia. In fact, Australian legislators have shied away from its’ introduction since the information contained in the tyre size provides tyre buyers with more useful information on a tyre’s performance.

I will explain why the UTQG ratings are not so useful.

There are three tyre parameters rated under the UTQG.

• Treadwear ( tread wear compared to a standard tyre, expressed as a percentage. e.g. 200% wears half as fast, so tread wear is twice as good)
• Traction, (AA, A, B or C with AA best)
• Temperature ( A,B,C, with A being best)

All these comparisons are made against a “standard tyre” – now an obsolete design and construction dating back to the period when the law was introduced. All the modern steel belted radials “rate the socks off” this standard tyre.

It is a classic case of technology overtaking legislation but adding to the cost.

The evaluation for treadwear is done on a 640 km road course for a total of 11520 km, – one of the most boring road test drives ever. Every effort is made to keep the testing conditions as standardised as possible.

However, with this type of testing there are variables which may not be taken into account. Such as a heavily siped pattern (many knife slots in the tread design, often only half pattern depth), which will wear faster at first than later, but may give good braking. Also lug design off road patterns may develop unusual wear patterns early in the tread life which even out as the tyre wears down (or not). As these are being compared to a highway rib design on a highway – the comparison may not be valid.

Similarly traction ratings to the standard are made on a highway tyre surface. Off-road tyres generally have a rounder tread profile to reduce the rubber volume in the shoulder/buttress area which helps it run cooler, but promotes faster wear in the centre of the tread design.

Off-road tyres also have a lower pattern to void ratio- the pattern grooves are wider than for a highway design, so initially they too may wear faster than later on in their tread life.

Temperature ratings grade a tyres’ ability to dissipate heat when tested under controlled conditions on a specified indoor laboratory test wheel. However, as speed rating is a much more specific way of expressing a tyres’ ability dissipate heat – size branding will give provide more information than the UTQG rating.

Finally, a word of warning. The Australian Design Rules placard on the vehicle stipulates the minimum speed and load rating of the tyres fitted to the vehicle, both when new, and through State legislation, for the replacement tyres. Lurking always in the background as the enforcer is your insurance assessor. Fitting the wrong tyres may void your insurance cover!

Extended Track Width

One of the limitations placed on modifying a vehicle’s suspension, is restricting the increase in track width to one inch (25.4 mm, so some States say 26 mm., some 25). They would, wouldn’t they! Can’t even agree on how to round out metric conversions.

So I’d better define track width first. It’s the measured distance from the centreline of the crown of one tyre, across the vehicle to the centreline of the other on the opposite side.
So why do they bother? As part of the program to discourage such modifications, State legislation prohibits tyres extending past the width of the body-work (though you can buy mudguard flares). Even with those, you might still get knocked back because of the fall-back position, which is to also legislate for track width limitations.

There is a sound reason for the limitation. The wheel is supported by two bearings on the axle. The inner bearing is load bearing (only), and is cylindrical in shape, whilst the outer bearing, which is tapered, is a thrust bearing. When the car is loaded up by either extra load, or cornering, the stresses on the wheel rise, and are transferred to the bearings. The outer bearing is designed to cope with sidethrust, the inner bearing with load carrying.

When the wheel track is widened, generally by fitting wider wheels and tyres, more load is transferred to the outer bearing, as the centre of the load is moved outboard. Wheel manufacturers can compensate for this by moving the centre disc of the wheel (the nave plate) further outboard, so that the extra width is carried inboard as well as outboard. These might be known as “deep dish wheels”.  It is possible to find wheels with the same hole spacing, which will fit on your hubs, but the offset may not be suitable for your car. Incidentally, the wheel is located on its “Bore Hole” the centre hole, and the wheel nuts are located on studs at a specified “Pitch Circle Diameter” (P.C.D.), which is what you find in wheel makers’ catalogues.

The life of the outer bearing is important. Should it collapse, then the car’s steering can be greatly affected, and it can lead to loss of steering control. Designers of front wheel drive cars are well aware of the risks, the front wheel drive is already “busy” steering and driving, so they applaud these limitations. A note of caution- if your FWD car’s drive joints screech when you corner hard, please get them replaced. If they collapse, you might end up in “big trouble”. How much trouble depends on the design of the front end.

Reading a Tyre’s Message

Tyres are a very tradeable commodity in today’s international trading world. Some countries use them to buy other currencies, and soon after a currency has been devalued, you will find tyres from there on your docks.

They are all made to similar technical, performance, and dimensional standards through a series of interlinked Tyre and Rim Association Standards world-wide. The major bodies are Tyre and Rim Association, U.S.A., Japan T & R, Australian T & R., and E.T.R.T.O. (Europe). So a Romanian made tyre fits a Peugot in Brazil- it’s no accident. These Standards cover the basics, but individual countries may require other information to be available to the tyre consumer. So manufacturers try to cover all the bases, by putting a veritable essay on the tyre sidewall some of which is relevant, some ( a lot), is not. For example, U.S.A. legislation requires performance information on tread wear, wet road/braking information. The ratings given are very high, the reason being that they are related to a bias ply tyre, which hasn’t been around as a passenger tyre now for over 20 years! Tyre technology improvements have made them meaningless.
So let’s stick to the basics of a tyre size code. Let’s take 195/75R15 92H as an example. Now I have to get a little bit technical, because measurements of a tyre are made under strictly controlled conditions, otherwise they too, would be meaningless.

195- dimensions in millimetres of the section width of the tyre (with raised lettering excluded), when mounted on a specified rim ( the measuring rim), inflated, stabilised for a period because they grow a little bit when inflated for the first time), and then measured at its widest point. The rim has to be specified, because section width increases with increasing rim width. Every young car enthusiast knows that!

75- the ratio of section width to section height. Section height is measured vertically from bead ledge to the crown of the inflated tyre.

R- The tyre is of radial construction. Nowadays, they nearly all are. If there is no “R”, then they are not Radials.

15- the nominal rim diameter. “Nominal” because it’s not exactly 15 inches, and how would you measure it on a taper anyway (see interference fit article). In fact to measure a rim accurately requires specialised equipment called a ball tape. Certain manufacturing tolerances are permitted, so each rim diameter and profile has its own ball tape measure, with the tolerances built in.

92. A code for the load in kilograms that the tyre can carry at a specified maximum pressure, in this case 630 kg. If for example, it was 96, this signifies that the tyre can carry a higher load, at a higher inflation pressure, so it has a stronger casing. The smallest code is 0 (zero), which carries 45 kg. That’s probably a wheel barrow tyre. The largest (so far) is 279, which carries 136 tonnes (136,000 kg), the size of which you have probably guessed as those giant machines that work in the mines.

H- A code for the speed capability of the tyre at specified load, temperature and pressure. In this case, it’s 210 km/h. The range of speed categories go from A1 (5 km/h) to A8 (40 km/h) for slow moving equipment. Then B to Z covers 50 to 300 km/h in 10 km/h steps, with 0 (Zero) omitted because it might get confused with O, and H out of sequence (because it was there first!) H comes after U, then follows V, Z, (same reason), W, and Y. X is omitted because the first radials (Michelin) were designated X, and this could breed confusion.
Z is different. ZR with no other speed category means the tyre has been designed to fit the performance of a particular high performance vehicle. They’re on your Ferrari or Lamborghini. ZR plus a speed category following, carries that speed category as defined e.g. 275/40ZR17 93W has a maximum speed of W (270 km/h)

Compare all the tyres at a particular size on CarbonBlack.com.au

Reading your Tyre’s Message

Tyres are a very tradeable commodity in today’s international trading world. Some countries use them to buy other currencies, and soon after a currency has been devalued, you will find tyres from there on your docks.

They are all made to similar technical, performance, and dimensional standards through a series of interlinked Tyre and Rim Association Standards world-wide. The major bodies are Tyre and Rim Association, U.S.A., Japan T & R, Australian T & R., and E.T.R.T.O. (Europe). So a Romanian made tyre fits a Peugot in Brazil- it’s no accident. These Standards cover the basics, but individual countries may require other information to be available to the tyre consumer. So manufacturers try to cover all the bases, by putting a veritable essay on the tyre sidewall some of which is relevant, some (a lot), is not. For example, U.S.A. legislation requires performance information on tread wear, wet road/braking information. The ratings given are very high, the reason being that they are related to a bias ply tyre, which hasn’t been around as a passenger tyre now for over 20 years! Tyre technology improvements have made them meaningless.

So let’s stick to the basics of a tyre size code. Let’s take 195 /75 R15 92H as an example. Now I have to get a little bit technical, because measurements of a tyre are made under strictly controlled conditions, otherwise they too, would be meaningless.

195 – Dimensions in millimetres of the section width of the tyre (with raised lettering excluded), when mounted on a specified rim (the measuring rim), inflated, stabilised for a period because they grow a little bit when inflated for the first time), and then measured at its widest point. The rim has to be specified, because section width increases with increasing rim width. Every young car enthusiast knows that!

75 – The ratio of section width to section height. Section height is measured vertically from bead ledge to the crown of the inflated tyre.

R – The tyre is of radial construction. Nowadays, they nearly all are. If there is no “R”, then they are not Radials.

15 – The nominal rim diameter. “Nominal” because it’s not exactly 15 inches, and how would you measure it on a taper anyway (see interference fit article). In fact to measure a rim accurately requires specialised equipment called a ball tape. Certain manufacturing tolerances are permitted, so each rim diameter and profile has its own ball tape measure, with the tolerances built in.

92 – A code for the load in kilograms that the tyre can carry at a specified maximum pressure, in this case 630 kg. If for example, it was 96, this signifies that the tyre can carry a higher load, at a higher inflation pressure, so it has a stronger casing. The smallest code is 0 (zero), which carries 45 kg. That’s probably a wheel barrow tyre. The largest (so far) is 279, which carries 136 tonnes (136,000 kg), the size of which you have probably guessed as those giant machines that work in the mines.

H – A code for the speed capability of the tyre at specified load, temperature and pressure. In this case, it’s 210 km/h. The range of speed categories go from A1 (5 km/h) to A8 (40 km/h) for slow moving equipment. Then B to Z covers 50 to 300 km/h in 10 km/h steps, with 0 (Zero) omitted because it might get confused with O, and H out of sequence (because it was there first!)H comes after U, then follows V, Z, (same reason), W, and Y. X is omitted because the first radials (Michelin) were designated X, and this could breed confusion.

Z is different. ZR with no other speed category means the tyre has been designed to fit the performance of a particular high performance vehicle. They’re on your Ferrari or Lamborghini. ZR plus a speed category following, carries that speed category as defined e.g. 275/40ZR17 93W has a maximum speed of W (270 km/h)

Each tire has a speed rating based on how well it reaches and sustains a specific speed. A higher speed rating generally means that the tire will provide better handling. Things to think about when looking at speed ratings:

• The code indicates the speed capability after pressure adjustments.
• The higher the code letter, the higher the speed capability.
• Higher speed ratings confer greater ability to cope with severe conditions of speed and heat. They perform more reliably under duress.

Carbonblack TyreXchange displays a illustrated summary of tyre sizings as shown on your tyres.

With Rims, Inches rules!

After flirting with different systems, tyre size codes have gone almost completely metric. There are still a few relics around in R.V. and aircraft tyres, based on inches, but passenger tyres are coded in metric. All except the rim size, so really it becomes a hybrid of both. Why didn’t they get rid of the inches then.

The answer, is that there are just too many inch rims to change. For example, U.S.A. makes over 60 million rims a year, and they last forever. Rims are used all over the world, from Afghanistan to Zagreb, ending up on all sorts of vehicles. They all rely on the fit between tyre and rim, which is designed to tight tolerances to hold it on. It just got too hard to effect the change. Conservatively, it would take 50 years or more of confusion and danger to change the world over to all metric. It was easier to call it a “nominal rim size” in inches.

There are in fact, metric rim sizes, which are designed to be used with only two types of tyres- Michelin TRX and its derivatives, and Dunlop Denloc run flat tyres. These are specially matched tyres and rims, of different diameters to the inch norm. They must NEVER be fitted to inch coded rims.

The rim diameter is known as the “nominal rim diameter”. A fourteen inch rim doesn’t measure fourteen inches anyway, because of the designed interference fit between the tyre bead and the rim ledge. It is measured only with a specially designed ball tape, because the rim ledge is a taper, and dependent on just where the measurement is made on the taper, you yet a different result, so a tape measurement is useless. For example, a 14 inch rim (nominally 14) has a specified diameter of 13.968 inches, with a plus and minus tolerance from 13.9838 to 13.9523 inches. The rim taper leads the tyre bead up to a radiussed flange which stops the bead going any further.

There is a further complication. So that the bead will not unseat readily if deflated accidentally or purposely, a “safety hump” is placed inboard of the flange, of diameter just below the final specified ledge diameter. During fitting, the tyre is inflated until the pressure is sufficient to slide the lubricated beads over the hump. Placed far enough down the taper to allow the beads of the tyre to seat on the ledge between flange and hump, it holds the deflated tyre in position hopefully long enough for the motorist to slow to a halt.
The logic is that you can still steer the car until the beads become dislodged, after which it becomes uncontrollable.

While it is possible to design a tyre/rim combination to pass this bead unseating test (see Dunlop Denloc above), the easiest way is to incorporate these safety humps. The bead unseating test is a requirement of the Australian Design Rules, and the rims used in the test procedure do not have a safety hump- the tyre is a tight fit anyway.

As with all things engineering, an unfavourable combination of tolerances can result in a very tight, or very loose fit between tyre and rim. Some tyre makes have the reputation amongst fitters of being difficult to break the seal. The design manual for the engineers from that particular tyre maker may specify a tight squeeze of the rubber and fabric between bead hoop built into the tyre, and the rim. Others are a little more relaxed about it. Different styles, or applications even within the one make, may be tight or loose, dependent on how the tyre is to be used.