grey ghost

on my 986 s, I have run the Hoosier A6 in 245/35/18 height 24.7",275/35/18 height 25.5"and 285/30/18 height 24.7 on my the 245 and 275 were on my 18x7.5 stock wheels with a 1/4" spacer. the 245 clears everything, the 275 rub's on the fender liner polishing it and the lower spring purch. the 285 were mounted on a 18x9 stock rear rim mounted on the front. it will rub the liner polishing it. I have not tried the 255's which will be my next purchase.

I did Mount a 285 on the 7.5 but did not like how they looked on the rim. Did not run them at any events.

I like a very sharp front on my cars, for this I run alot of pressure up front in the middle 40's and about 10lbs lower in the rear. A lot of others run they pressures diffrently. personal preference for most .

just my 2 cents
Rob

balefire

Somehow I missed this post.
I'm considering a 285/30/18 V710 on my 18x8 front, stock offset, camber -0.75. I would also go with a 305/30/18 V710 in the rear.

Sounds like the front will likely "polish" the fender, the strut, or both. Does "polishing" preclude running it, or is it more of an intermittent light "haze" during hard cornering only. Thanks!

utkinpol

I am not sure if it will help you or not, I just got CCW c14 rims
18x9 +50 (7" backspace), 18x12 +69 (9.25" backspace).

So I got 265/35/r18 kumho v700 on front rims and it barely fits, it actually fits only because I have GT3 LCAs and -2.4 degree camber points top of the tire inside into wheel well. no way 285 tire can fit there. that is on 9" rim with 50mm offset on a 997 car.
and that`s on those custom wheel - 285mm tires on a stock 8" rim with 57mm offset (even if you will manage somehow to mount that 285mm tire on a 8" rim) will rub at fenders.

IMHO max tire that will work on stock 8" and 10" rims are 245/305 and 305 is somewhat too wide for rear 10" wheel. but you can get toyo ra1 in those sizes and they are of correct diameters so it will work better imho than odd 285/305 combo. to put 285 in front you really mush roll up your fenders and put 9.5" rims in front. I think ccw makes such as well.

00r101

So, first results with the 275s on an 8" rim on the front of my 987. 1) They fit with a 5mm spacer. 2) My co-driver felt they were unpleasant - sloppy turn in and mid corner push. 3) I thought he ran pressures too low. They seemed better with higher pressures (33+). 4) Overall I was not impressed. I liked the 255s without spacers better. Could not take the spacers off the 275s as they would rub on the bottom of the spring perches. 5) I will give them another try this weekend at the DC Pro but I am not expecting much.

Paul E. Dodd

I don't think you'll ever get a 285 V710 to mount on an 8" rim. 245/35 V710's are a royal PITA on an 8" rim, I can't see how you'd ever get the V710 on there. The Hoosiers mount a lot easier for some reason. Many times have I picked up a partially mounted 245/35 V710 on an 8" rim from a tire shop and had to finish the mounting myself with lots of tire snot, guys jumping up and down on the rim, heat, and air pressure.

FWIW, there was a thread quite a while back from the GT3 guys running in SS (Peter Lier if I recall correctly). They found in back to back testing that the 285 on the rear was faster than wider sizes due to the better gearing. Your very tall 2nd gear is probably one of the biggest liabilities of the car (assuming it is similar to the 993), and a wider/taller rear tire only exacerbates this problem.

PedalFaster

It's pretty common, actually; I personally ran an RX-8 with 285 V710s on the stock 18" x 8" wheels for a year. You just need a good tire guy, preferably one who's used to dealing with Stock class autocrossers and our ridiculous demands.

00r101

Bringing this thread back to life for another datapoint.

This year I moved from 275/35/18 fronts on my 987 to 285/30/18 fronts on stock size and offset 18x8 rims and identical 285/30/18 rears on stock size and offset rims 18x9. They all fit without spacers! These are Hoosier A6s no info on Kumhos.

I like the way these tires work and wear better than the 275s.