Archive for June, 2008

Goodyear, the ACCC and Green Tyres

So Goodyear Tyre and Rubber have been pinged by the Australian Competition and Consumer Commission (ACCC) for making claims that their tyre was “green”, without being able to substantiate the claim. According to the ACCC, over the last two years, Goodyear Tyres made a number of representations regarding the environmental benefits of its new Eagle LS2000 range of tyres such as the production process led to reduced carbon dioxide emissions and the tyre would use less fuel on the road.

So what makes a “green” tyre? First, for the tyre experts amongst us, a “green” tyre is an assembled tyre that hasn’t been vulcanised yet. That’s not what Goodyear was about.

A “green tyre” can be summed up in three words- low rolling resistance. As a tyre revolves, it absorbs power, which is ultimately sourced from the fuel that you put in the tank. The lower the rolling resistance, the lower the heat generated inside the tyre, and the lower the fuel consumption. It absorbs power because it is distorting where it hits the road, and recovering its shape, during every revolution. All those little molecules are being made to spring back into shape (they’re elastic, but not perfectly so), and in so doing, they lose some energy as heat.

Fortunately, this resistance is easily measured on a dynamometer equipped with a torque reaction weighing head. Typically, a brand new tyre will absorb more power than when it is “run in”. Fit a flexible coupling to the hub so that the tyre can have its pressure adjusted on the fly, and the effects of raising the inflation pressure can be easily measured – less distortion, less energy consumed, less fuel required to drive it. Which is why motoring authorities and environmental advocates advise motorists to inflate their tyres to the higher of the pressures placarded on the vehicle.

How does the tyre engineer set about designing a tyre specifically optimising its low rolling resistance?

Easy!!!!! Just reduce the volume of rubber in the tyre, by making the tread depth less, and reducing the rubber volume in the shoulder/buttress area of the tyre- the thickest part. They do this by rounding the profile of the tread arc to lighten the rubber gauge in the shoulders. Unfortunately though, a rounder tread radius does not wear as well as a flatter radius, though there is a limit to how far you can go with this too.

So the end result is a lighter tyre, absorbing less power, that doesn’t go as far. But there is another factor- it’s called the Australian country road, with its broken road shoulders, and potholed edges. Lighten the tyre, and the durability under country conditions is less. How do I know? Been there. Done that.

During the oil shock of the seventies, when oil when to the equivalent in today’s dollars of (shock horror) $80 a barrel, the company for which I worked brought out a tyre based on these well-known design principles. Unfortunately, by the time it was developed, the oil shock was over. Stuck with a slow moving item, the fateful decision was made to release them in far away Australian markets where they would not disrupt the existing price structures- i.e. ‘ the outback”. The result- disaster!

What is interesting today is the number of tyres that now carry words in their branding that implies that they are eco-friendly, as part of the pattern code, or whatever. Since nearly all tyres are fully imported, and manufactured all over the world, the ACCC.may have a busy time checking out such claims.

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June 27, 2008 at 8:37 am Leave a comment

South Pacific Tyres to close Somerton Factory

There is only one factory producing tyres set to continue for the time being anyway, in Australia. South Pacific Tyres, which is wholly owned by Goodyear, announced that the Somerton factory, on the northern outskirts of Melbourne, is to close by the end of the year. The truck tyre factory on the same site closed some years ago. All Goodyear and Dunlop tyres will be imported in future, to complement the raft of tyres already imported. That leaves Bridgestone in Adelaide as the last remaining tyre manufacturer.

The Somerton plant was originally opened by B.F. Goodrich of the U.S.A. in the sixties, but couldn’t make a profit, because the bias tyres they made were going out of use. Ownership passed to Olympic Tyres, which re-equipped the factory to make steel belted radial passenger and light truck tyres. Olympic was swallowed by Dunlop in 1979, and Dunlop formed a partnership with Goodyear 8 years later. Goodyear finally bought out their partners earlier this decade.

Closure follows a long line of departing manufacturers, starting with Hardie, Goodrich, Firestone, Olympic Dunlop, and now Goodyear.

From the sixties, Australia had its own production facilities for materials to make tyres, mostly located in Victoria. British Nylon Spinners at Bayswater, Australian Carbon Black (Cabot) at Altona, and Columbian Carbon in Sydney, Australian Synthetic Rubber at Altona, and most recently, Australian Wire Industries (Baekhert of Belgium) at Geelong have all closed in the past decade or so, leaving the tyre manufacturers to source materials from overseas. Since nearly all (except steel) are sourced from oil, the dramatic increase in costs of materials has obviously affected cost of production. Material cost is a substantial part of the manufactured cost of a tyre.

June 26, 2008 at 7:31 am 2 comments

Our experts on: Tyre pressures and new cars

You’ve all seen those car carriers barrelling along the highway, with seven to ten cars clinging precariously, so it seems, to the back of the prime mover-trailer combination. They move along, don’t they!

But what of the bright shiny near cars clinging on, sometimes at acute angles?

Look closely as you pass (if you can), and you will see that their wheels are clamped solidly to the ramps with wide webbing straps. Even though they may jiggle up and down on the trailer, there is not much “swing and sway” of the cars or R.V’s on the ramps.

This is because their tyres are inflated “hard”- around 42 psi – the so called “shipping pressure”. This stiffens the sidewalls of the tyres, and reduces lateral (sideways) movement of the car right up there on the ramps.

When the cars get to the dealership, they are unloaded and given a pre-delivery check – one of the extras that you pay for as part of the new car buyer’s deal.

One of the items on the list is “Check air pressure”. All that the car detailer has to do is make sure that the tyres have air in them. They may just look at them, and if they are not flat at the bottom, then that may be good enough.

The customer picks up his new car, and notices immediately that it is much harder riding, and a lot twitchier, than the demo ride he had before he signed up.

First step then is to check tyre pressure and reduce it to where it should be – the pressure specified on the tyre placard, which normally is either on the side of the driver’s side door, or on the door pillar.

There is a range of pressures specified there depending on the loads and speeds that the vehicle is going to be subjected to in service. So make a decision, based on your knowledge of how YOU are going to use the car, and drop the pressure to a normal range.

This will have two effects- it will give you a more comfortable ride, and make the car less sensitive to steering input- less twitchy. It will also jar the suspension less, and increase the resistance of the tyre to abuse such as hitting a sharp pothole at speed, which might (rarely) cause a blow-out.

June 13, 2008 at 1:26 am 1 comment

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!

June 10, 2008 at 10:42 am Leave a comment

For the woman who has everything

And the wheel,’ said the Captain, ‘what about this wheel thingy? It sounds a terribly interesting project.’

‘Ah,’ said the marketing girl, ‘well, we’re having a little difficulty there.’

‘Difficulty?’ exclaimed Ford. ‘Difficulty? What do you mean difficulty? It’s the single simplest machine in the entire Universe!’

The marketing girl soured him with a look.

‘All right, Mr Wiseguy,’ she said, ‘you’re so clever, you tell us what colour it should be.’

– The Restaurant at the End of the Universe, Douglas Adams

All those experts out there may know that tyres are black because of carbon black but there are still many of us tyre buyers who didn’t know. And there are probably a few more people that didn’t know that you could buy lavender scented wheels from Kumho – the Ecsta DX . If you live in the US, Kumho also lets you expand your nasal repertoire with not just lavender – you can also buy jasmine and orange scented wheels.

Apparently the scent only lasts approximately a year but I guess if you looking for a gift for the woman who has everything, its a possibility.

June 3, 2008 at 3:47 am Leave a comment