Tyres/Wheel size

[Guest]

Just looking at changing my tyres and currently have 225/45/R17s on the front and 255/40/R17s on the back . I have checked the other forums and are the fronts too big ?( should they be 205's) I have no problem with them and they do not rub. Currently running on Contis which I am happy with.

Thanks David

 

[964rh]

David

shouldn't be a problem at all. I run 225's at the front on 7" rims. 245 at the back on 9" rims.

I have a slight run on full lock but this has not damaged the tyres or bodywork in anyway. Use mine on track most of the time.
On my C4 the front tyres help with the understeer no end.
Rob

 

[Guest]

Rob,

Thanks for the reply. What tires are you running? Use contisports for more of a smoother ride as I don't track day her much.

Thanks

David

 

[964rh]

David

I'm running Dunlop SSR's at the minute.

I did have Conti sports on when I first bought it but completely trashed them at my first trackday.

If I ever get a spare set of wheels/ust use for for the road again I'll either use Contis again or give the Bridgestone S02a's a try.

Rob

 

[Hacki]

David,

if you want a smooth comfortable ride take Contis. I recommend the smaller front tire (205 / 50), the wider ones make the front end more nervous.

Regards

Hacki

 

[Guest]

Hacki,

Sounds interesting. Can i swap my current 225 's for 205's? I am ssuming that the wheel size is the same?
I have noticed that the front tyres do slide a bit and lack the grip. Thought that they might need changing even though they have alot of grip left!

Appreciate your help.

David

 

[Hacki]

David,

wheel size should be 7 x 17 front and 9 x 17 rear. With 205 / 50 front and 255 / 40 rear that should be perfect, the best compromise for daily use and fun.

Changing tire and wheel sizes means to think about a full new set up. (Ride height, springs, dampers, camber, toe-in (better not), sway bars, spacers...)

Don´t know how old your tires are, a fresh set of rubber makes a big difference!

BTW, all mentioned above is my experience with several C 2s, don´t know anything about C 4s.

Regards,

Hacki

 

[Dave Wilkinson]

David,

The 225/45 tyres are, technically, too big for the 7J wheel. I know Rob has said above that he has them fitted but the tyre doesn't sit nicely on the rim. The 205 tyre is the ideal. Rob's point about the improved understeer is correct but it would be better to fit the 225 tyre to a 7.5J rim.

Regards

Dave

 

[Hacki]

David,

I totally agree with Dave, 225 won´t sit nicely on 7" rims. I run 225 / 45 front tires on my Cup car, but that´s with 8" rims front, rear is 255 / 40 with 9,5" rims. That´s a great combination also, but the wheels are hard to find.

If there´s too much understeer, new rubber (all 4!) might help. Having changed the rear tires twice while front tires are still the first set means that the front end looses grip due to the old tires. Wheel camber, toe-in, etc. should also be checked to make sure that everything is correct. A 964 is a sensible thing concerning that.

Last but not least: tire pressure. My experience is that 2,5 bar (don´t know psi) all four tires is fine for daily use with 205 / 50 x 17 and 255 / 40 x 17. Track days are a totally different story.

As soon as all the details are set up precisely eyerything will be perfect!

Enjoy,

Hacki