In my search for more front grip, I have come up with the following options. They're all within ~10 revs per mile which I really doubt will affect PSM or the viscous coupling.

225/40R18 Stock 829 revs per mile
235/40R18 818 revs per mile
245/40R18 809 revs per mile 20 revs per mile different
245/35R18 840 revs per mile
255/35R18 831 revs per mile

295/30-18 rear runs 833 revs per mile
315/30-18 rear runs 817 revs per mile

Seems the 255/35 18 is the best diameter match. Anyone know if this will fit the stock 8" rim and not rub the fender?

I have both 7mm and 15 mm spacers if backspacing is an issue....

BTW I used this calculator: http://www.1010tires.com/tiresizecalculator.asp

 

I would like to know myself. ..

 

I am running a 265/35 in front on a 9inch wheel with -3.5 camber

rear 335/40 on a 12.

If it aint rubbing it aint big enough!!

I have increased the front rubber on this car by 2 inches!!! Huge help for the track.

If you are only running around on the street I wouldnt push it?

 

Here's a repeat of a post I made about using
any of those online tire size calculators:

Never, never use any online 'tire size calculator' if you are
dealing with close tolerances, such as trying to prevent
rubbing, or if you need exact diameters. They all mean
well, and are simply designed according to what the tire
size nomenclarure is *supposed* to mean, but in the real
world there is a wide range of variance between what a
tire is designated as and what it's real dimensions are.
For the real facts you have to go to the tire manufacturers
spec sheet. I have seen two different 245/45-16 tires differ
in diameter by 1/2 inch *from the same manufacturer*!
They were just different model tires. Recently one tire
manufacturer stopped making it's 305/30-18. Now they list
a 315/30-18. *It's the same tire*! They just decided that
the actual tire dimensions were closer to the 315 meaning,
so after 6 years they just changed what was printed on the
sidewall.

Go to the tirerack site and look up the tire model you're curious
about, and find the spec sheet. Eg:

http://www.tirerack.com/tires/Spec.j...li&model=PZero

If you look closely at all the different types of PZero,
PZero Nero, PZero RFT, PZero Rosso, PZero System etc.

Choose a tire size and compare the different spec sheets.
You can find diameter differences of over a quarter inch
for the same-spec'ed tire.

 

Point taken Joe. The tire calculator shows that the TT and GT2 tire combinations are about as close as you can get. the 255/35-18 seems to be the best front tire match, but is hard to find and is a stretch both in terms of fit on the rim AND fender clearance. I'm going to look for 245/35-18 and see how it goes...

 

Guys. Help me out! I have an opportunity to pick up some 255/35R18s that match my rear tires to a T (brand and model) on closeout, but I have to act fast. Will they fit the 8" rim and clear the fender?

 

i think a 245 would be about max for a 8'' rim. but continue your homework.

 

it's going to be very close on the rubbing issue when you turn. I run a 235 on my hre's and thats close at full lock

 

Ok guys. Tires are ordered. Got the last 2 conti sport contact 2s from America's tire on closeout at a ridiculous deal. This tire is shoe in for the stock 295 rears in terms of diameter so PSM and AWD should play nice.

If it works, and there is any room to play, maybe I'll try to work on some GT2 rims for the 1/2" extra width.

Will update in a week or two.

Keep your fingers crossed for me!

 

Ari,

They will fit bro. I gave it a try today worked like a glove

 

Sweet. now I'm getting excited.

I'm now officially a wheel and tire dork. I've spent more time on spacers, tires, etc...

 

Tires are on the rims and in the garage. Probably be a few days before test fit and drive. It will probably work, I was running 15mm spacers with the 225s with no issues at all. I also have 7mm spacers for an in betweenie...

 

Just wanted to bump this and see if ayone had other opinions. I recently rebuilt my wheels and had larger barrels going on the rear. We found out one front barrel was cracked so we used the old rears. I'm running an 18x9.5" up front now. Want to run 255's and wanted to see if anyone else was

 

if you're running 315/30/18 rears run 265/35/18 fronts. Do the radiator brackets mod up front and you'll have no problem fitting them

 

i'm actually still running the 295/30 in the back. But the 255/295 sumo's match exactly.

Got tires mounted today, have them back on the car, but haven't dropped it and driven yet