wider tires on the rear

[meganall]

a friend has got 225 40 18 on the front and 235 40 18 on the rear will that affect any of the drive train

[Peter D]

And the car is ???. AWD, FWD, what. Regards Peter

[neilos100]

They are also slightly larger in diameter.......the rear are 8mm larger than the fronts.
Wonder if his insurance company are aware? I'm willing to bet that his policy would be voided by them in the event of an accident if they dont know!

[meganall]

sorry peter, its same as mine a 2.5 tdi quattro

[meganall]

i know if you have 2 different sizes on the same axle you could end up with diff probs but not sure with the 4x4 system

[neilos100]

Well, Audi recommend changing all 4 tyres (on a Quattro) at the same time to avoid any size discrepancy between wheels to avoid undue wear on the transmission system. I would assume that different size wheels front and back will have the same effect and damage could be done to the differential.

[Peter D]

Your diff is doing overtime as all tyres should be the same size and profile. Regards Peter

[Duncan Clarke]

Your diff is doing overtime as all tyres should be the same size and profile. Regards Peter

From the perspective of the diff surely just the radius needs to match. Getting wider but lower profile such that they have the same overall radius overcomes this.

However, how it would affect the ABS, traction control or general handling I do not know.

[Peter D]

But the tyres in question are not the same rolling circumference. The profiles are the same so the rears that are wider will be larger. Regards Peter

[Duncan Clarke]

In this case yes, but I was referring to a general statement that the diff was under stress due to different profiles which is not completely true. It's the rolling radius that must match even if profiles don't.