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Reading some of the 'what tyres are best for my car' Back Room posts got me thinking, how do car manufacturers choose which tyre to supply on the vehicle from new? Does the development of a car take one, many or no brands of tyre into consideration? Or is it all down to cost?
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Most quantity manufacturers will test with several makes of tyre;yes, costs will come into it but when you're talking millions of tyres,all the quotes will be very similar.Tyres are tested by the car manufacturer for grip(wet & dry),noise,durability,rolling resistance and a few other lesser criteria.
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Does the development of a car take one, many or no brands of tyre into consideration?
Many. Using a sole supplier could stop production if there was a supply problem.
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L\'escargot.
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For a given size the performance premium brand tyres will be very similar.
During the design stage the car manufacturer will work with a couple of preferred supplies. The tyre co. will supply a computer model of the tyre - which will incorporate information on parameters such as compliance, sidewall stiffness etc etc. The chassis designers will incorporate this into their computer model of the car's suspension. Using this model they will be able to understand how the chassis will respond to different types of input etc - probably working with tyre co 'applications engineers'. This helps them decide on the best tyre profile for the car.
During prototype testing the test cars will be fitted with sample tyres and the predictions of the computer model will be verified. Other issues such as tyre noise (difficult to predict due to standing-wave patterns in the sidewall) will also be investigated.
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Interesting one this. A friend had a Celica 190 VVTLi and when the original P Zeros wore out, he had them replaced with the same again as he was delighted with their performance. The replacement tyres were nowhere near as good as the originals, particularly in the wet, and the car was significantly more understeer prone in all conditions.
He was told by his local tyre dealer that Toyota's OEM tyres are a different compound to the aftermarket ones, and that the OEM compound was not available to buy as a replacement. He also said there wasn't much difference and you shouldn't notice it.
How true the latter is I don't know, but I can confirm the difference after the tyres were swapped out (they also lasted 5k longer than the originals suggesting a harder compound).
He then went for Bridgestone Potenzas which were much more like the original tyres in behaviour and life.
Cheers
DP
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He was told by his local tyre dealer that Toyota's OEM tyres are a different compound to the aftermarket ones, and that the OEM compound was not available to buy as a replacement.
I seriously doubt this is true.
Car manufacturers would work with preferred suppliers to arrive at a suitable fitment - probably against a guarantee of certain %age of the business. Once the vehicle is in production then other companies would be invited to tender (against a requirements spec) for the remaining business. I don't think any companies would be interested in a 'bespoke' compound other than for very special high-value appications.
What is more likely is that the manufacturer made changes to the compound over the years.
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Remember that the manufacturers' tyres were probably only made a few days before going onto the vehicle;what you buy from your local tyre shop may have been sitting around in warehouses and storerooms for a considerable time.
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And then someone goes out and spends a fortune on wheels/tyres because they look "pretty".I always used to order my cars with steels because 1.the size was the same;2.the weight was the same;and 3.they didn't get nicked!
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interested in a 'bespoke' compound other than for very special high-value appications.
That reminds me didn't Bridgestone work together with Honda to develop a new tyre specifically for the original NSX. IIRC they were unidirectional and different sizes front and rear, so each corner required a unique tyre. Obviously not the normal way of doing it...
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The early Mk.III Cortina was only available in GT form with Bias-belted tyres;people who fitted the equivalent size in conventional radials soon found out why-tho' the majority of drivers would not reach the extremes used in testing.
A sample test for stability.Drive down the test track at 80mph.Take both hands off the wheel,with one hand rapidly put on a half turn of lock and release the wheel.Count the number of oscillations of the wheel before the vehicle becomes stable again.Repeat for the other lock.
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I once had a 1984 BMW 318i from new; came with Contis, I think. At some stage I replaced the fronts with same-size/rated Michelins, and the car felt quite different, awful even.
Which led me later, when I had a VW Golf GTI that needed new front tyres, to ring up VAG tech folk and ask them what brands they recommended. The dumb broad I spoke to - technical by bottom - didn't know what I was on about, said just fit the right spec. Since when I've always replaced like with like, on the grounds that doing otherwise could cause big dissatisfaction.
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& of course, if you're a big enough car maker & you design a poor handling model, which has all the associted charecteristics you'd expect from a 4x4, as long as you've selected the right tyre supplier, you can level all the blame at them - when you'r cars start rolling over!!
VB
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Tyres are generally revised many times during their life-cycle. I usually keep the same make/type of tyre, so notice that when I get a new pair, they are more often than not different from the pair on the other axle. They have extra small sipes added in the blocks for example. I remember this on Pirelli P7, I remember P6000 have different Nylon/Ply/Rayon/Cord ratings, and Goodyear F1s change in treadwear and country of origin.
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I actually do believe it to be true - particularly as the car was Japanese. Going back to my motorcycling days, it was well known that the country of origin on a certain tyre affected it's performance. I think one of the tyres was made in France, I can't remember where the other was made. Same tyre model, different country of manufacture, completely different performance of grip.
If this happens with motorcycle tyres, why shouldn'tit happen with car tyres as well?
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I actually do believe it to be true - particularly as the car was Japanese. Going back to my motorcycling days, it was well known that the country of origin on a certain tyre affected it's performance. I think one of the tyres was made in France, I can't remember where the other was made. Same tyre model, different country of manufacture, completely different performance of grip. If this happens with motorcycle tyres, why shouldn'tit happen with car tyres as well?
I can quite believe that the same series of tyre would be made with slightly differing compounds depending on time and place of manufacturer. Like in any other business, tyre makers make slight alterations to compound, processes and design in order to reduce costs and bring about other improvements. This is different to saying that they would make a special formulation of the tyre just for OEM fitment - at least on 'mainstream' cars.
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The OEM Pirelli P6000s fitted to my 2003 V70 were so average in some respects and below average in others that I feel they can only have been fitted on the grounds of low cost. As an old tyre design with development costs recouped eons before, no doubt they were sold to Volvo for peanuts. The Goodyear Eagle GS-D3 F1s that I fitted as replacements are in a strikingly different league in all respects; perfectly suited to the chassis characteristics of the car, they stand as the best road tyre I've ever used.
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