Dealer installed wrong side tires - uneven wear? diff probe?

[carlflorida]

So, I am a brit out here in the US and am dealing with a bit of a joke issue. Bought a certified 2011 z4 in November 13, noticed vibration from back in September 2014, took it to local dealer (one i bought it from is out of state) and they told me that the rear of the car has two different sized tires. One is correct - the rear left is the factory size, but the right rear is actually a front tire incorrectly fired to the rear.

Two questions...

225/35/19 vs 255/30/19 tires on rear.

1) could i argue that the different sized tires have caused the inside edge of the larger tire to wear unevenly (it is corded)

2) do you think I may have a problem with the clutch packs in the diff. down the road? I mean, its ran 13,000 miles now with one rear tire 30mm wider than the other and a 5m higher sidewall profile

I can't even get the dealer to admit they made a mistake fitting a front on the rear, they've given me a copy of the certified pre-inspection report saying the right tires were fitted, but obviously i didn't fit a wrong one (haven't changed them since bought). Utterly disgraceful to be honest, i am speaking with dealer principal in the morning and i am think I am right with my concerns, but would appreciate any input.

thanks for your time - sincerely appreciated.

 

[mr wilks]

No matter what vehicle or what country each axle should always have a matching sized tyre & wherever possible matching brand & some would even say matching tread depth & pattern .
The mismatched set up you mention can only have a adverse effect as you suspect so i would pursue the supplying dealer & definitely get a pair of 255 30 19s fitted

 

[simonlpearce]

Are the wheels staggered fit? Is it possible they just got the axle mixed up and you can swap the front and rear round? At very least you should check both fronts too.

 

[Mister T]

I thought the Z4 had an open diff so no clutch packs to worry about.