BuyPirelli Posted February 25, 2011 Report Share Posted February 25, 2011 Curious, but quite often when I replace a worn set of tyres, I notice a considerable difference to the characteristics of the car. The worn out Goodyears I posted up about the other day came off the rear of my Mondeo they were fine bar a little extra noise at low speeds. However the new PS3's I have fitted have brought a new lease of life to the car. Its much quieter (this I expected), the ride is so much smoother and the car seems to float along on the motorway - almost as if it had done 50,000 less miles. The thing is, I had no previous complaints about the Goodyears, they seemed fine... I know there are differences between tyre makes, and I never previously had any complaints, its only now I have fitted the PS3's I can tell a big difference. So is it the make of tyre, or the fact one is over 3 years old, done many many miles and various track days? Quote Link to comment Share on other sites More sharing options...
Sagitar Posted February 26, 2011 Report Share Posted February 26, 2011 Curious, but quite often when I replace a worn set of tyres, I notice a considerable difference to the characteristics of the car. The worn out Goodyears I posted up about the other day came off the rear of my Mondeo they were fine bar a little extra noise at low speeds. However the new PS3's I have fitted have brought a new lease of life to the car. Its much quieter (this I expected), the ride is so much smoother and the car seems to float along on the motorway - almost as if it had done 50,000 less miles. The thing is, I had no previous complaints about the Goodyears, they seemed fine... I know there are differences between tyre makes, and I never previously had any complaints, its only now I have fitted the PS3's I can tell a big difference. So is it the make of tyre, or the fact one is over 3 years old, done many many miles and various track days? The concept of fatigue in materials is normally associated with changes in the structure of the material as a result of large numbers of load reversals. I suppose it will happen eventually in elastomers but I would have thought it unlikely to be responsible for the change you have noticed. Elastomers harden with age as a result of chemical changes and that will play some part, but three years is not over-long for a standard summer tyre that hasn't been abused. It would be much more significant for the softer elastomers in a winter tyre. The change of tyre design and construction could do it, but wear alone will create big differences and because it happens gradually you are less likely to notice the change in behaviour caused by wear, whereas fitting a new tyre introduces a step change that is much more likely to be noticed. You don't say what level of wear there was on the old tyres, but if they were down to (say) 2mm, this would mean a lot less flexibility in the tread than with an un-worn tyre. If you think of each tread block as being like a small beam that is cantilevered from the body of the tyre, then the amount of lateral deflection for a given load is proportional to the length of the beam i.e. the tread depth. The effect is not linear however, but is proportional to the cube of the length of the beam. So a 7mm tread will flex about twelve times as much as a 2mm tread for a given load. It's not surprising that they feel different. Quote Link to comment Share on other sites More sharing options...
Tony Posted February 26, 2011 Report Share Posted February 26, 2011 Concider that an answer Quote Link to comment Share on other sites More sharing options...
BuyPirelli Posted March 1, 2011 Author Report Share Posted March 1, 2011 Interesting, thanks for the input. Anyway I can't hear ANYTHING from these PS3's on the rear, any noise must be drowned out by the Goodyears on the front. Quote Link to comment Share on other sites More sharing options...
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