I didn't post this in the "wheels and tires" section because my question pertains specifically to solo/track use...

Despite what seems to be the general consensus that squared setup works best, I'm going want to try wider in the rear (my car oversteers as is, so wider in back shouldn't hurt).

Wondering whether 315/30/18 will have too much sidewall bulge (ie have excessive sidewall roll) on a 10.5". Tires are NT01. Attached are pics of 275/35 NT01 on said 10.5". They look slightly stretched to me. So, with the proposed 315's I'd theoretically be adding 40mm total width, or 20mm per side. By eyeballing it, I'm guessing/hoping that wouldn't present much of a bulge, wouldn't soften up the sidewalls too much. To my inexperienced eye it appears it might be pretty close to square.

But... 10.5" is the minimum wheel width recommended by nitto for the proposed 315. And I've read a couple of accounts where people expressed that 275/35/18 nt01's seemed to be sloppy (have too much roll) on 9.5", but handled great on a 10.5 (Evo folk, probably talking about fronts). So, if 275 is too floppy on a 9.5", I can't help but suspect 315 would be even floppier on a 10.5".

Does the fact I'm wanting to put this (perhaps slightly bulging) setup on the rear (as opposed to the front) help mitigate my concern?

Hoping to get feedback from someone who has actual experience with similar sizing... Thanks

 

I'd want an 11 or 11.5"...I ran a 315 Hoosier on 11/12's.

 

Yeah, I know a wider wheel would be better. Currently can't afford a pair of decent 11"s. So, given that I'm currently stuck with 10.5" all around, and that my car oversteers a bit, the question at hand is would 315rear(w/slight bulge)/275front perform *much* worse than 275 square? Keeping in mind that my season is almost over and I'll likely be able to afford a pair of 11"s to transplant the 315 to by the spring? I'm not trying to be competitive to the point of shaving tenth's of a second off my lap times, wondering if the bulge would be "so wrong" that things would be much worse than that...

 

I'd rather run a 275 on a 10.5 than a 315, but ideally you should be using a 285....maybe even a 295.

 

Yeah, would if I could, but got kind of hooked on idea of NT01's for my purposes (good compromise between grip and longevity in a DOT-R, or so my internet research has led me to believe), and they don't come in those sizes. I know they don't heat up quickly enough to be truly competitive at autox, but I'm more interested in time behind the wheel than competitions, and currently just attend practice days where we have multiple runs, often close to back-to-back. Last event I did 50 miles (in just a half day). Under such circumstances figured NT01's would get warm enough to perform and last much longer than a dedicated solo tire...
Given your recommendation maybe I'll just run 275 all around until I can afford some 11"s, then I'll just have a spare pair of 275's for the front. Thank you.

 

Are there any other tires you have considered? Will these also be "street" tires? The NT01 gets eaten up real fast in street use. But does not get hot very hot for track use, it is very strange.

 

I run 295/35/18 on my 10.5s. dd

 

Not for street in general, but probably driving to/from events, maybe stay on them a few days before/after.

Considered gobs of tires. You have a better recommendation?

Considered many max perf summer tires (RE11 being top contender), but really wanted to experience that extra notch of lateral g force I thought only a DOT-R could provide, and, more importantly, got the impression the NT01 would actually have greater longevity on the track (er, what's the proper way to refer to an autox track? A "course" perhaps?). So, decided I needed to have separate dedicated street/track tires.

Being a novice, reading that they were not very sensitive to heat cycling made them sound very appealing. And, they were relatively cheap- ~$225 for 275/35/18.
How long might they last as DD? 5k miles? Doesn't rain here in Summer, so probably could get away with it if I wanted to burn $.

Haven't used them at an event yet. My first experience with a DOT-R tire, so nothing to compare to, but the little I've driven them on the street they grip better than my DD PSS's (with less grace) when ambient temp is in 80's and tires aren't heated. Read people complaining about NVH, but I have a heavily modded suspension and noise was already bad on any perf street tire, barely worse on the nittos.

 

on my 10.5's I run 295/30/18's and it fits flush or very slightly less than flush with toyo R888's.