Rear Tire Size

That is the rear size I use, with stock in front!! I am very happy with them!! As for spacers you need 15mm in the rear (also what I use)

 

For stock wheels, I only believe in the original tire size. Keeps the tire tighter and more consistent handling.

 

295/35/18 is very close to the stock size.

 

Over an inch wider, which allows the sidewall to flex a bit more. Close to stock diameter though.

 

Loved the switch to 295/35/18's. And they look mean.

 

My understanding was that on the rear if you went to a 285/35 you would not need spacers. In some postings I have seen guys say they went up to 295's without spacers.
Any thoughts.

 

I think you can run 11mm spacers with 295's. I have 15mm spacers with my 285's. I went 285 because the sidewalls were huge on the stock 265/40's. The 285's are just a tiny bit smaller radius which will give you a 'tiny' bit more bottom end acceleration . I think the 285's are the correct width for a 10" wheel.

 

I went 295 with no spacers, handles just fine after a heat cycle or two.

 

You can go with 15mm spacers in the rear with no problem and 255/35 fronts but the fender lip would have to be rolled. I 've run this setup for 3 year with no problem.

 

Agreed. If the engineers at Maranello thought a 295/35 would improve handling/balance, they would have put them on their to begin with.

-R

 

I don't disagree with going to a larger tire though, I'm all for more rubber. But personally I'd only do it with a matching increase in wheel width.

 

I'm not so sure.............

 

Beg to differ. Tire is too small for the rim. When Mario Andretti did a track test which included a 355 for Road & Track he had to radically LOWER tire pressure at the rear. Why? In his words, to get more tire to the ground! Porsche Turbos of the same generation used a 10" rear wheel with a 285. Fits perfect. Also, 512TR and M use a wheel just half an inch wider (less than 13mm) yet use a 295, 30 mm larger than a 355 tire. Never assume and never just follow. Your car will handle better and SAFER with a 295 in the rear than with a 265.

 

Ive had the 295 35 18 on for years and it is incredible. Bridgestones of course and no spacers.

 

My car:

Rear - 295/35/18 w/ 15mm spacers
Front - stock w/ 15mm spacers

I'm not saying spacers are needed, just letting you know my fittment.

 

Wheel sizes have 3 critical measurements(not 2)...these are width(flange to flange),diameter, and flange height(i.e. J[.68"] or K[.77"]..etc.).......the maximum flange to flange wheel width should be equal to the tire tread width...any wider and it creates a bad rim seal(dangerous) and forces the tread to assume a convex shape causing abnormal tire wear and a reduction of control......

 

Isn't yours a really good replicar though??

 

Use of spacers load the suspension differently than what oem design was setup for.....you may be able to get away with this on a street car but for race applications shock valving and spring rates would need to be changed, along with sway bar and camber adjustments.

 

Well, it's really, really, good though.......

I also dialed in about 2 degrees neg. camber in the rear.

 

That is true, the wheel gets more leverage with a spacer. It is a small percentage increase of the entire a arm length. So as bca said, street should be ok and as for racing .....well the addition of 'unsprung' weight does not help either so most racers should/would 'retune' their suspension.