Can anyone shed some light on overall handling changes when running 255's on the track? The additional rubber on the road sounds good theoretically, but if increased under steer is the result, I'm not sure I want it. It may be slower around the track, but I like some rotation from the rear end. Experience???

 

I haven't tried them but if you are considering using a 255 with the stock wheel it is not recommended. Even with 245s on the stock wheel you will be sacrificing feel for additional rubber on the road. If you are talking about wider wheels disregard.

 

Matt - I've used 235/45 stock tires, 245/45 Falken Azenis (old style), and 255/40 RA-1s on the same track with the same suspension set-up. The 235s and 245s were on the stock wheel and the 255s were on 5zigen 17x9 inch rims. I didn't notice any difference between them in terms of understeer/oversteer. With my set-up (-2.5 camber front, -1.5 camber back, 0 toe front and back, Tanabe GF210 springs), the car is essentially neutral with all these tire/wheel combinations.

There was a difference in terms of ultimate grip, though. The order of performance is RA-1>A046>Falken. It is possible that the RA-1s are a little slower on the straights due to more aero drag and contact patch friction, but that is hard to quantify without direct measurement with a number of replicate runs on the same day (which I didn't do!). My car has minimal power mods, so with a more powerful car that probably wouldn't even be a consideration.

I also haven't experienced any interference with bodywork with any of these tires/wheels except for the Falkens at one autocross where there was a left turn that required full steering lock. In that case, I got a bit of rubbing on the inside front fender well.

I've used all three tires on the street. I have to say that the A046s are the most pleasant for day-to-day use. I wish they weren't so expensive!

 

Ever since I wore out my stock Advans, I have been running 255/40/17 RA-1s. I do a lot of track days and have used like 5 sets already. They fit just fine on the 17 x 8 Enkei wheels. This set up was recommended to me by John Mueller of Road Race Chassis, and it works great.

 

Although I still haven't decided on my final wheel choice, I'm leaning towards the Work Emotions or WedsSport SA-70's. Both would be in the 17 x 9" size. Regardless of who's correct in the 255-tire size fitting the 8" wide wheel, I'll be running 9's, so no worry.

 

Interesting...so you didn't give up anything going to the 255s? I think it would be awesome to fit those on my stock wheels but I'm still a skeptic. Every tire manufacturer says 235s are the optimal size for a 8 in. wheel. I've seen you post quite a bit about driving so I'm assuming you have experience and would be a good judge of this. Did you ever try the 235 RA-1s? I'm curious to see what your impressions of the 235/45 and /40s are.

 

You will be fine with the 255's on 8 inch wheels. Also, stay away from the 235-45-17's as there is noticebly more sidewall flex with the taller tire. I HATED the 235-45 RA-1's on the track.

 

I ran the 255/40/17 RA1's on stock 17x8 wheels. They flex a bunch but they grip pretty well. Unfortunatly I did not try 235 RA1s.

I now run 255's on 17x9 and there is a huge difference in sidewall flex, alot less now. I have not tracked yet with this combo so I am not sure if there is anymore grip.

Percy you need to change your TR340 sig.

 

Manufacturers tend to be very conservative in their recommendations because that's what their lawyers tell them to do. If you are running 17 x 9 wheels, you can fit 275 RA-1s on them. Kent Jordan, who won 12 races in a row in the NorCal SCCA ITE class last year in his Road Race Muellerized EVO ran 275s on 18 x 9 wheels for a good part of the season, before switching to 305 Hoosiers on 18 x 10 (or maybe 10.5 -- not sure). Kent runs 1:39 at Laguna Seca, 1:45 at Sears Point-Infineon, 1:59 at Thunderhill and 1:22 at Streets of Willow. Can't argue with those numbers.

 

1:57 at thunderhill.

 

Right. He ran 1:59 in an earlier race and then improved on it later in the season.

 

Thanks for the reminder B.....