Tire size concern

[Harddrive]

So I've had my 06 B7 QTR for about 3 months now. Its currently at 104k. I bought the car from a Manhiem auction, had it tuned and shipped to me in Africa. Its been fun especially with the APR stg 1. Yesterday I was looking at the tires with a view to changing out the back 2 and discovered that 3 of the tires were 225/50/R17 while one was even 215/50/17. I checked the driver door sill and it listed that they should all be 235/45/R17.

I'm a little worried now cos of the whole rolling radius thing and how that could affect the tranny blah blah blah..

So I guess my question is, is this a big issue? Car drives just fine so far.

[p0isin]

If all tires had the same amount of tread depth, then the 215 will be 5 mm less on either side of the wheel in height.

I think that would be like driving with three brand new 225/50r17 tires and one almost bald 225/50r17 tire on the car.

[Brillo]

Here is my opinion. There is about a 1.5% difference in the rolling diameter between the 215 and the 225 tires you have. This is not enough of a difference to cause a problem with the differentials. I would not have the mismatch unless all four tires would need to be replaced in the next 5000 miles. You don't say how new the tires are but i would be tempted to get rid of the 215 and replace it with a used 225 that is in good shape. The same brand would be ideal but at least make sure that the load carrying capability and speed rating are the same as the other three. The 215 width tire is on the verge of too narrow for the stock A4 wheels. The 225 by 50 is a very good tire for our cars. It is slightly taller than the stock tire (235/50/R17) which will give you a marginally better ride due to more sidewall height and will get you slightly better gas mileage. Your speedometer may be slightly more accurate because Audi speedos are optimistic. The downside is that you will have softer handling in the corners, again due to the taller sidewall. Depending upon how you drive this may not be an issue.

[Harddrive]

Thanks guys, the tires are all approaching their useful thread life, particularly the rears. I just swapped out the 215 with the spare tire which was a 225 with about half its thread depth left so I'm golden [:d]

Glad to know the 225s won't be an issue. Lots of roads here suck so having to switch to lower aspect tires like the 235/45 would have been [:(]