Mismatched Tyres
 

I have been given two Avon ZV3 235/40 ZR17 tyres which I was thinking of fitting to the rear axle of an 02 WRX Bugeye. The front treads are Bridgestone Potenza's 225/45 ZR17. Does anybody know what effect/s (if any) this tyre mismatch could have on the car and if this was an ok thing to do???

That gives too much difference between the two.

Tyre height of 93.6 mm for the 235/40, versus tyre height of 101.25 mm for the 225/40, just under 8 mm difference. That's far more than the 1 mm difference that Subaru recommend as the limit.

Even if we asumed that their 1 mm suggestion was unnecessarily conservative there's no way that 8 mm would do the centre diff any good, quite apart from any effects on handling caused by the different characteristics of the tyres.