Bridgestone sidewall cracking

[RF man]

Mine have gone the same way on my BMW, Bridgstone Potenza run flats, have only done 18k and 3 years old, they are in worse condition that the fronts which are 4 years old. Same sunlight exposure, but rears are wider and lower profile 255x19x35, not sure if it has any significance.

 

[brandwooddixon]

I've been told in the past that tyre compounds include an additive that helps to keep the rubber flexible and prevent cracking, unfortunately, its only released once the tyres get up to the correct temperature.

Hence, a tyre that is used regularly on long journeys will not crack and one that isn't will.

Lack of use and exposure to sunlight exacerbates the aging process and promotes cracking (just ask any caravan owner).

In any case, I take the view that, if the rubber has started to perish like this then the tyres should be replaced irrespective of tread depth. Hence, my wife's low mileage Micra never wears out the tread before the tyres are replaced.

Any new tyre, no matter how cheap, sold to UK spec. is less costly than than a potential blow out and accident whilst driving in my view.