Opinions on upsized tires

[black_box]

Need new summer rubber on my 2000 Box S bone (stock suspension and wheels). Currently has stock 225/40/18 and 265/35/18. Thinking of going to 235/40/18 and 275/35/18 for a bit more ultimate grip (rear end came out on me last summer in the mountains) and for more rim protection when parallel parking (not daily driver though). Tires will probably be Pilot Super Sports, driven hard out-of-town, roadtripping and some DEs.

Experiences, opinions?

[John Howar]

I have been happy with Toyo RA1's on my 97. I run 235x17 front and 275x18 rear. Very good grip for track days, wear rating of 100 means they will wear faster than the Michelens, mine last one season.

[black_box]

I wound up with 235/40 & 275/35 pilot super sports, they feel pretty good, although the car has a little bit more understeer now.

[AR_Groundzero]

I just replaced my Dunlop Direzza tires with Michelin Super Sports at the stock sizes of Front: 225-40-18 and Rears: 265-35-18. It feels like the car has more body roll and the rear tires look very large to me from rim to top of tire. I feel like my Dunlops had a lower profile look. Does anyone have any opinions/experience with this. I have added high res pictures of both the front and rear tires of the car.

Front Tire

Rear Tire

Thank you for any of your help and assistance.

[4agdtym]

I wound up with 235/40 & 275/35 pilot super sports, they feel pretty good, although the car has a little bit more understeer now.

Now that you've driven all summer with these tires ... what do you think? Have you fixed the understeer? Do you have factory alignment or something else? Have you played with air pressure? Any thoughts about how the extra width fits the rims and the amount of tire roll under hard cornering?

I use the Yokohama Advan Neova tires. I really like them for dry traction and steering response. I have the alignment with near zero toe and 1 degree negative camber in the front and 1.7 degrees negative camber in the rear. I get a bit oversteer - but only a bit when I really drive hard.

[Scott Scott]

Switched from Toyo T1R to Yokohama Advan AD08; 225/40/18 and 265/35/18 on Fikse Alloys. Love the new Yokohamas on a dry track - very predictable.

[grover]

I run 245/35R18 in front and 285/30R18 rear with Kumho V710s (r-comp) with no issues. Clearance is REAL tight, though, especially in front on the inside. Also, I'm running aftermarket wheels, with slightly different offsets, which gives me an extra +4mm in front and -9mm in the rear. I don't think these tires would be an issue at stock offset, but different tires have different profiles, so it's really hard to say. I've heard of people running 285s all-around with Hooser A6 but found it actually was slower than 17s with 245s all-around.

I DD and autocross Dunlop Z1 Star Specs and have nothing but great things to say about them; they've been discontinued and are on clearance now if you can still find them. Dunlop Z2 is supposed to be out in a few months and by the numbers, will blow away every summer tire presently on the market, so you might want to wait. Track alignment and GT3 sway bars should help you tune your understeer.

Edited December 31, 2012 by grover