Archive for October, 2009

Goodyear Wingfoot teams with Aussie Lightfoots

Helen and John Taylor, an Australian couple who have made a speciality of setting records for low fuel consumption in the USA, have done it again.

Converting their miles per American gallon to litres per hundred kilometres yields an astonishing 4.155 litres /100 km in their 2009 Volkswagen Jetta diesel.
This time they were riding on Goodyear Fuel Max tyres, and improved on their 2008 figure by a further 15.4%!

This consumption is more fuel-efficient than the most popular hybrid, and shows what can be done with modern diesel technology, careful preparation and fuel saving driving techniques.

Follow this link to learn more.

So how do they do it? Tyres obviously play a part, since Goodyear sponsored their 9000 mile circuit of the States. We are constantly told to maintain high air pressures if fuel savings are desired, but what are the limits? A tyre usually absorbs around 2 KW just rolling around under load at 120 km/h.

The safe maximum pressure of a tyre is shown on the sidewall, and for a passenger tyre is in the 36 (Standard Load)- 42 (Extra Load) p.s.i. range. It will not burst at 43 p.s.i., but a maximum is specified to maintain a margin of safety for tyre abuse such as potholes and rough edges. So economy drivers go to the limit, or beyond. A tyre with 15 p.s.i. pressure pulls nearly twice the rolling resistance as the same tyre at 33 p.s.i. at 120 km/h, the higher pressure giving a fuel consumption improvement of about 4%. Steel belt radials have the lowest rolling resistance, too.

Staying with tyre design, a narrow tread width, shallow tread pattern, and a rounded tread arc radius all contribute to lower rolling resistance, and with specially compounded tread rubber it is possible to design a tyre to maximise the reduction in a tyre’s contribution to fuel consumption.

Preparation of the vehicle using low friction lubricants, a well run-in engine, diesel fuel designed to give “more bang for the buck”, and other tricks of the trade are also used, such as refuelling at low ambient temperatures, like the middle of the night.

But driver’s skills are required to get good figures. Feather-footing, low top speeds, shift points carefully calibrated, travelling when wind speeds are low, smooth car surface with no unnecessary projections, climbing hills carefully (just making it over the top), and no air-conditioning are techniques used. Depending on the rules of the contest, in most cases coasting downhill, and drafting, is prohibited. In certified fuel economy runs conducted in Australia, an independent observer travels in the car to prevent this.

Want to know more on the tyre angle? In our All About Tyres section you will find Green Tyres are Black, David’s ten tyre tips, and Exploding Cylinders which will expand on rolling resistance and fuel consumption.

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October 27, 2009 at 9:01 pm Leave a comment

Brad Pitt falls off his Chopper

So Brad Pitt fell off his “chopper” motorcycle. Unfortunately for him as he was in view of the paparazzi.

Hasn’t anyone told him that motorcycles with very high castor angles on the front forks (laid back at an acute angle) have very poor stability at low speeds.

They fall over.

That’s why BMX bicycles and trail bikes have their front forks ALMOST vertical, so they can be manoeuvred at low speeds. If they are vertical, then steering at high speeds becomes very twitchy.

In contrast, high castor angles steer very much in a straight line at higher speeds. Think Peter Fonda (who? say the younger generation) and his “Easy Rider” motor bicycle. Man, was that laid back.

That’s why shopping trolley front wheels always have a small, but positive castor angle on the steering wheels. Otherwise they just jiggle from side to side, and are a pain. Hence why Brad felt!

Your car’s “alignment” incorporates all of the above to keep you safe and in control, and hopefully without the paparazzi.

October 27, 2009 at 8:45 pm Leave a comment

Wire Failure – from Ipods to Tyres

FAILURE – not a pretty word is it? Yet I had two failures this week, both due to FATIGUE.

My steam iron cord failed just where it comes out of the rubber tube at the end of the handle, and my I-pod just where the ear bud cord comes out of the plastic.

Why there? The iron had a long rubber tube, and a spring shaped thingy as well wound around it. Yet it still “failed” there. The wires inside were charred, but very fine. The I-pod wires were just fine, and broken, if you get my drift.

Why do they make them out of such fine wire, you were going to ask. Well if they made these flexible leads out of a thicker wire, they would not last long at all. Witness when you want to bend a coat-hanger till it breaks. It doesn’t take long, and it gets quite hot to hold where you’re bending it.

But like the iron and the I-pod, it will always break first where it is being flexed the most. This needs a bit of explanation.

So it is with tyres. If nothing else destroys it, such as road damage, the tyre will fail where it flexes the most. Wrong! It fails first where the greatest differences between flexibility (the tyre sidewall) and rigidity (the bead/lower sidewall); or upper sidewall to tread and belt area exists. It fails due to fatigue because by then, it will have rotated and flexed at these parts of the tyre, on average 30 to 45 million times for a passenger tyre, and 100 to 130 million times for a truck tyre.  Truck tyres go further because they’re inflated harder, so don’t flex as much, though they may have worn out three tread lives by then- tyre speak for been retreaded twice.

After that, the carcass of the tyre is not worth retreading because it is approaching the unreliable stage due to fatigue. Reliability is highly prized- and highly priced you might say.

Passenger tyres go at least twice as far as they used to 30 years ago, so a large chunk of the fatigue life built into the tyre is consumed in the first tread life. This is why retreading of passenger tyres has declined to such an extent. It is also why the motorist should look after his tyre pressures. The flatter or more overloaded the tyre, the more the tyre deflects as it rotates, and eats into its reserves against the ultimate failure- fatigue.

Incidentally, the wires in the steel belts of tyres are cables of wire made up if strands of fine wire, just like in the steam iron. The wires in the bead, which locks the tyre on the rim, don’t flex, so they are more like a coathanger wire. The iron had lasted quite well really- at least the fatigue beat the corrosion inside the steam chamber!

October 27, 2009 at 9:21 am Leave a comment

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.

October 22, 2009 at 5:25 am Leave a comment

For the Techies – How Hard is Rubber?

Natural rubber is the sap of a rubber tree, converted to a solid by coagulating it with acetic acid. Rubber used in tyres is generally the product of an oil refinery.

When combined with chemicals such as carbon black, antioxidants, and hosts more, sulphur added, the mixture subjected to heat and pressure, it comes out vulcanised. Sulphur makes the process irreversible.

Part of the “black art’ of making up the various mixtures used in the many components of a tyre, is varying the “hardness” of the rubber compound. For example, the rubber around the bead wire is compounded up to be quite ‘hard’ since it doesn’t move when the tyre rolls along. Conversely, the sidewall is ‘soft’, because it moves around a lot- it flexes.

However, most attention is paid to the tread compound, because this affects the wear and grip of the tyre because it’s the only part that hits the road.

How is it measured?

The tool used in the trade is a Shore A Hardness Durometer. Never heard of it? There is a range of them, designed to measure the hardness of different materials.

It simply is a small hand held tool with a domed plunger that is pressed into the surface of the rubber. The reading obtained on the quadrant scale when the needle is first pressed squarely against the rubber, is the hardness. Some cautions though- rubber hardness varies with temperature, it softens as it gets hot- every race car driver knows that. Also, the rubber ‘creeps’ away from the plunger, and as you hold the plunger against the tyre, the initial reading falls away.

So that is absolutely no help when the salesman tells you that the tread of the tyre that he’s selling is hard and long wearing. You might get a clue by pressing a reasonably blunt pencil into the rubber. If the rubber is “soft” the indentation might stay around a while after you remove the pencil. If it’s “hard”, the indentation might disappear quicker than for a softer rubber.

That’s not much help either, is it?

This is because there are many variations on a theme to make a tread compound. But beware of the salesman who tries to tell you that the tread is long wearing, and hard, and gives good grip, particularly in the wet. That’s nirvana, and hasn’t been achieved yet, to my knowledge.

So treads and sidewalls might have 1-2% sulphur, bead wire compounds 6% sulphur, and the old fashioned black ebonite ruler that granddad had, contained 35% sulphur, and was as hard as the hobs of hell.

I did say that it was a “black art”!

October 21, 2009 at 6:58 am 1 comment

CarbonBlack TyreXchange on A Current Affair

Thanks for those of you who continue to promote CarbonBlack to your friends and to the media!

ACA logo

Last month A Current Affair on channel 9 covered the CarbonBlack’s tyre research and tyre dealer directory. It was all about looking for new tyres and the fact that only few people knew about their tyres. ACA had done an interesting  study showing that the less informed you are the more money you could possibly pay for your tyres.

Then, the show explained how you could research tyres and compare tyre dealers on CarbonBlack.

This is the main reason why tyre dealers join CarbonBlack:

CarbonBlack tyre dealers offer the right price and the right service. They are reputable dealers whose purpose is to satisfy customers rather than to sell by any means. That’s why our dealers accept to share information and to be reviewed on CarbonBlack by their customers. They understand today’s role of social networking as the most effective way to market, and that a longer term customer is worth more than a one-off over-paying one.

Tyre Buyers: On the old subject of price, remember to always compare apples to apples, or tread to tread. When replacing your tyres you get what you pay for.

  • Know what you’re after: safety, performance or cost savings – you will not get all three in one tyre
  • Do your research on the tyre dealer. Read reviews (eg. on CarbonBlack)
  • Ask questions. Be sure you understand what you’re buying.

An informed customer is an empowered one.

The whole segment on CarbonBlack is available in the link below.

http://aca.ninemsn.com.au/article.aspx?id=860857

October 8, 2009 at 8:51 pm Leave a comment