GT3 v 996 TT front tyres and rims??

[robinm]

The 996TT has 225 tyres on 8 inch rims.
The GT3 I believe has 235 on 8.5 inch rims.

Can you run the 235s / 8.5 rims on a TT without contacting the bodywork? Any other negative effects?

Is there any improvement in handling?

[kevinday]

More information is needed before a decision can be made. Firstly the wheels themselves:
Are they the same diameter?
Do they have the same stud pattern?
Do they have the same offset?
Then the tyres:
The full tyre measurements would be needed not just the width, because the diameter and profile are used to calculate rolling circumference.

[seandudding]

I beleive the offset of the GT3 and TT Wheels are different.

[robinm]

Rim diameters are the same at 18 inch

Tyre profiles are 225/35/18 - 996TT
235/35/18 - GT3

Stud patterns and offset not known

[PEVO]

width 235mm is only 10mm more than the 225 on the tt -hence you can probably just put 235s straight onto a 8" rim. This solves the problem of offset, etc. You also will not increase the rolling diameter of the wheel by much - about 8mm roughly, but this may be enough to rub on the suspension, plus it will throw out your speedo. Maybe go for 235/30??

[flemke]

If there is any chance of a clearance problem you'd be wise to measure the actual tyres by hand.
Tyre manufacturers do not seem to agree on what a millimetre is: there are amazing discrepancies across brands in the physical dimensions of what are nominally identical size tyres.

[kevinday]

The change in diameter between 225/35/18 and 235/35/18 is 7mm, this is 1.1% increase in rolling circumference, not really significant. The 235/30/18 option that was suggested is 16.5mm smaller in diameter, a 2.8% resuction in the rolling circumference, this is significant, I would not consider it.

Personally I would go and chat to a Porsche service centre and ask them what they think?

[robinm]

Got the profiles wrong. 225/40 and 235/40. Shouldn't make any significant difference to your comments, for which many thanks.

I wonder if anyone out there has tried different front tyres from standard on 996 turbo?