DavidNJ

Are you are running 275/40-17 fronts and 315/35-17 rears on 17x10+48 and 17x12+35 rims? Isn't 40mm a lot of stagger for road courses on an S2000 (even weight distribution, short wheelbase)?

s2000Junky

I listed my specs in previous post above but here they are again if you dont want to sift through. Ive run a 275 up front with this combo, but didnt like the overall steering feel and braking power diminished, as well as some rubbing issues when turning under compression. The tire is simply too tall for up front so switched back to a 255. The cars grip bias is still quite neutral overal as i set it up, but I also don't run a rear wing at track. My basic suspension components are 14k springs all around, 00-01 front sway, ap2 rear sway. Aftermarket upper control arms with camber adjustment front and rear. Front offset rca, front tie rod correction (similar to rear bsk)as well as steering rack spacers and rear bsk. Due to the front offset camber rca and upper control arms my net offset/track width up front is probably about 10-15mm wider then 10 +38.

Front 10 + 38 255
Rear 11.5 + 33 315.

The S2k has a fairly short wheel base but not Miata short, so a wider track width feels pretty great. Laterial adhiesion and confidence of an increased planted car is the benefit. I think the S2k is right in the sweet spot dimensionally to build upon for small and large courses.

DavidNJ

In another thread people competing in NASA TT4/TT5 where using 17x10+48 rims, which are similar to the STR 17x9+61 rims on the inside. Was wheel availability the reason to go with +38 rims in front?

Did you consider going to 18" rims, at least in the front? A 285/30-18 or 295/30-18 would be about the same height as a 255//40-17.

Manga_Spawn

Oh he has considered all of these things. I am pretty sure he said the detractor on 18's is the increased cost of the tires and wheels over 17's as well as they tend to be slightly heavier. The obvious benefit is there is a lot more choices for different tires in 18's since the sizes he is running on 17's limit to the nitto's he is currently running and maybe 2-3 others one of witch are hoosiers so not really a good street tire. For 17's up to 255's and 10 inch width are easy since there is so many choices for tires but beyond that it gets extremely limited. Really if someone were wanting to go a lot wider than a 255 18's make a lot more sense even with the added cost since tires are much more readily available and will continue to be readily available.

DavidNJ

The exact same problem for the Supra community, and I'm guessing other 1990s/early 2000s sports cars and sedans. My wife's car has 16" wheels. When new we had a selection of high-performance tires. Next time we may just have to bite the bullet and get new wheels.

Even in the 18" sizes, the selection can be limited. For example, in the old days, 265/35-18 and 295/30-18 were popular Supra sizes. Now it is hard to find a single tire model that covers both, although some can match the front with a 285/30-18 rear.

Manga_Spawn

The nice thing is some Porsches came with some of those sizes stock so there seems to be a wider range of tires. The 295 size especially. Junky used to run a 295/35/17 Kuhmo which was a size Vipers had if I remember correctly and that was the only car that ran that size hence it not being available anymore and why he moved to the 315's.

s2000Junky

295/35/17, but yeah. Same overall diamiter as a 255/40. Was a great pairing. No more though.

Moving to a 315/35/17 increased my options considerably compared to before. Same overall diamiter as a 275/40/17, so if im going to pay a slight gearing penalty I might as well get the bennifit of the added 40mm of tire width.

s2000Junky

My wheels are rpf1, but have been modified previously to maximize the available tire width I could run on a stock/modded fender s2k while having clearance for a bbk. The wheels were split and widened ending up with a custom width and offset Of 10 +58 front and 11.5 + 63. When I moved to the J's and CG fenders I added a 20mm spacer up front and 30mm in rear giving my current qouted net offsets.

I'm not completely apposed to moving to an 18 potentially in the future and would take advantage of having the ability to run a 285 up front if I did, but its not only a initial cost consideration of new custom wheels and keeping weight down, but a continued cost consideration. Just moving from 17's to 18's adds about $500 to the tire replacement bill. I go through a round of tires about every other year.

DavidNJ

For the Supra, I've been looking at the Forgestar in a not weird color. The Corvette crowd likes them and they are custom made in specific offsets...pretty much anything the buyer wants.

Cost of tires is always an issue. However, isn't the difference closer to $200 rather than $500.

Manga_Spawn

It depends on the tire and if there is a sale going on. Still not an insignificant difference on a wear item.