RobC4sX51

I have an '07 C4s X-51 that was ordered with GT3 wheels that are 8.5" wide front, and 12" wide rears. The TireRack shows the GT3RS (widebody) recommended tires are 245x35x19 front and 325x30x19 rears with these wheels. My rear tires need replacing. What tire size should I use? The current tire is a 305x30x19 and they appear way too narrow for these awesome wheels and TireRack does not recommend the 305s. Will I have clearance issues or speedometer error issues or PASM issues with the 325s? Thanks for any help.

jhbrennan

I have the same wheels on 2008 Turbo - run 235/35-19 and 305/30-19 with no problems - have 31,000 miles with about 12k on first set of Michelin PSS now on second set with about 3K. Set-up by Wheel Enhancement.

Edgy01

As I recall the 305 is correct for the 12x19 GT3 wheel. It's the exact same fitment as the Carrera Sports which are 11.5x19.

7500rpm

RobC4sX51, GT3s are RWD and probably need those wide rear tires. You have your front wheels helping you transfer torque to the Tarmac. IMO 245f and 305r is sufficient, even for X51. These sizes are fine on your wheels, but when you say the 305 appears way too narrow, did you mean visually or did you mean looking at numbers recommended by Tirerack?

7500rpm

Oh, someone needs to chip in regarding speed/odometer sensor location which is usually on the front wheel. If so, difference is negligible between 235 and 245. From what I have read regarding PASM, the front/rear circumferential difference would not cause problems. The reason I do not recommend those wide tires is because they take away some responsiveness, perform worse in the wet, more sensitive to rutted or uneven roads and could cause higher gas mileage and road noise. They are also more sensitive to poor wheel alignment.

RobC4sX51

7500RPM, thank you for your reply(s). I had not considered the road noise, added road rutt effect, or especially the wet wx issue. The speedo & PASM issue also seems reasonable. The narrow look of the tire issue is my opinion from looking at the rim bead & seeing how much further it "sticks out" from the tire tread area, esp compared to front tire. And TireRack said the 12" wheel should have at least a 315mm wide tire for safe & proper installation! I do use DWS tires in winter on Carerra Classic wheels (225/35/19f & 295/30/19r). Thx again.

mdrums

1st off GT3 rears do not fit wide body cars like your C4S. 2nd GT3 is narrow body car and uses 305 on a 12" wheel. 3rd GT2 and 3RS widbody use 325 but Turbo also wide body use 305.
For your C4S you need 305 in th rear.

RobC4sX51

JH, Dan, & Mike; thank you all for your input/advice too! The GT3 wheels fit fine on the car but I do realize that the "factory" offset is slightly different (53 vs 57f but rears are identical @ 51). I don't track the car (I know, shame on me but I have tracked 2 other 911s) so the tire choice is for pure street use. Did I mention it is a cab w only 11k miles on it! Will let you know what I get & any issues. Thx again. Rob

mdrums

Rob aren't the GT3 wheels really inset on your C4S wide body car? Unless you have GT3RS wheels???? But GT3 12x19 rears are offset et67. Turbo 11x19 are 51 and GT3RS are 12x19 et48. You say et51 which tells me a 11x19 wheel. Got a picture of your GT3 wheels?

jhbrennan

From the 997.1 GT3/GT3RS Product Info Book:
Wheels
GT3 Front: 8.5J x 19 ET 53
GT3RS Front: 8.5J x 19 ET 53
GT3 Rear: 12J x 19 ET 68
GT3RS Rear: 12J x 19 ET 51
Tyres
GT3 Front: 235/35 ZR 19
GT3RS Front: 235/35 ZR 19
GT3 Rear: 305/30 ZR 19
GT3RS Rear: 305/30 ZR 19

From the GT2 Product Info Book:
Wheels
Front: 8.5J x 19 ET 53 Rear: 12J x 19 ET 51
Tyres
Front: 235/35 ZR 19 (sport tyres) Rear: 325/30 ZR 19 (sport tyres)

RobC4sX51

I have GT3RS wheels then as the front offset is 53 & rear is 51 and they look awesome on the car. I will include a picture too. So should I consider 325/30/19 Mich super sports? Mich Pilot Sports are on it now (front & rear)? Thx, Rob

jhbrennan

Even though 325 shouldn't cause a problem, I'd stay with 305's. GT2 sizes are for RWD, TT sizes are for AWD - you don't want to cause any possible AWD issue.

mdrums

Ok makes sense with the RS shells on your C4S. 325's certainly will fit. Your will stil be with in the overal diameter specs between front and rear.

rijowysock

why dont we make this easy.. show us some pics..

325 is ideal... theyll fit fine. i ran 325 on narrow body 12+56

RobC4sX51

Pics of the GT3 wheel and offset!
Rob