RobertV

Quick question: my niece has a 2011 A5 and the service writer is telling her that she has to replace all four tires because she has different brands on the front axle vrs. the rear axle. I always understood that it is best to have all four being the same, but if needed as long as you have the same brand on the axle you wouldn't damage the torsen system. Am I correct or all wet on this one?

MiMitch

you seem correct, the fronts on an A8 wear quicker on the front, effectively making them "different" than the rear even when they are the same brand.... i could be wrong here, but if the fronts are the same diameter as the rear their shouldn't be an issue.

ide be going to a different tire place where they arent trying to up-sale the hell out of you... just my opinion, and im assuming the tires are the same size despite being different brands.

MiMitch

if the tires are as miss matched in size as the ones in the pic.... ide get new tires though.....

RobertV

Don't see how it would be problem

superswiss

Audi does specify to use the same manufacturer, size and thread pattern on all 4 tires. If you use different tires, then you have different wear rates and wear patterns and things can potentially get out of tolerance. Quattro allows for a 1% difference in tire circumference between all four tires. With all the same tires this translates to a 4/32" difference in tread depth. If you use tires from different manufactures or different thread patterns then the tires wear at different rates and if you don't watch it you may all of a sudden be over the 1% tolerance, especially if the tires have different circumferences to begin with. Tires from different manufacturers even if they are the same size don't have the same overall diameter. This is the theory anyway.

TSHong

Like all the previous post have stated, as long as the size are the same and have similar wear, your niece is ok. Is it optimal, no. Will it damage the A5, absolutely not. Coming from running retail tire stores for more than 25 years.

MP4.2+6.0

The permitted wear delta front to back is a couple of percent (more than 1% as I recall than other poster references). But as noted, that's a pretty big delta anyway, usually only seen if you used different sizes front to back.

Real issues are more how it feels/handles with mismatched tires and treads front to back, and possible traction differences in stopping, especially in emergencies. Less of an issue with modern cars with ABS and ESP, but still theoretically not the best. But having BTDT in a few younger day cases, at some point if it is all you can afford or it gets to be a beater, then you live with it but also drive in poor conditions knowing tire set up may not be top drawer.