ZDan

Oops...

DTP525

I wouldn't mind running a very soft compound tire such as a Hoosier A6/ Yoko005 Soft in a 315 on a S2k for a 20min race. The Hoosier A6s in a 295 square setup I ran for 6 hot laps had grip from lap 1 until the last lap with a moderate scrub in on warm up lap. They were scrubs as well. Doesn't take much heat to get that compound to operating temps. I don't know if it'll last for 20mins, but would definitely not fall off as quick as a 245mm A6. There are very quick Miatas running 295 A6s at A/X. That's like an S2k running 335s...yes it looks goofy, but some ppl will take the goofy with the FTDs. I'm not that extreme, but I do believe tire width matters. Compound always trumps width but the marriage of the two has lots of potential.

s2000Junky

Looks like I missed the cut off by 5mm for this thread. I am running the widest rubber you can on stock trimmed fenders/body though. 315+ is functional over fender territory. The inner shock tower housing to out fender edge is only 12.5mm on the S2k. That doesn't account for tire profile on rim width, camber/alignment and wheel path under susp compression, which all takes up more room.

Corey Maurer

On my car with the over fenders I had measured 13 inches exactly, I figure it this way, a 315 tire is 12.4 inches wide (theoretically) so if I were to run a 12.5 inch rim in the exact offset needed (haven't done the math here just yet don't have the car around to measure) THAT would give me enough inner clearance being that the tire would stretch on the rim just the slightest amount so that the rim could be flushed (an maybe poke a very slight amount) outside the fender, giving me probably 1/2-3/4 inches clearance on the inside, remember, this is NOT a track car, it is really a street/show setup, and if this setup didn't work I would have no problem going to a 295 with stretch..

Corey Maurer

Done a bunch of math, and looked at other setups, what works, what's too much for my taste, and come up with the following specs.. I have one more measurement to make, I need 2.3 inches inner clearance more than my current setup

Front 18x11+55 with 275/40/18
Rear 18x12.5 +60 with 315/30/18

It won't be till mid/late summer before I can get into a purchase (just trying like hell to get the car back on the road right now) but this setup WILL be happening!

ZDan

275/35-18 fronts would be a better fit, unless you really want the fronts to be 1.3" taller than the rears!

11.5" is max recommended wheel width for most 315/30-18 tires.

fyi

Corey Maurer

I don't care what's "recommended" this for the last time is not a street car, stretch is okay by me..

And yes my mistake on the 40 sidewall I meant 35

ZDan

Just making sure. Obviously, if it's NOT a street car, OR a track car, and some stretchie/pokey is desired, cool. But since this *is* intended as the "official" 300+mm wide thread that will possibly be used as a guide by others, I'll just comment that if I were buying $300+ tires I'd stay within manufacturer's recommendations...

Yer welcome!

Seeing that the BFG Rival is available in 275/35-18 and 315/30-18 has me thinking about possibilities on the RX-7...

Anyway, f@#king off now...

CrackerMacker

I love the banter!

s2000Junky

Hey as someone who is running 11.5" wheel at +63, you might want to double check your inner clearances. I don’t think your going to have enough inner clearance at +60 with a 12.5" wheel regardless of tire, especially since yours are 18's. You need to measure from the shock housing because that’s where your wheel and tire are going to make contact. I had to bang in the inner shock tower and fender a few mm where the rim and tire would touch. I took off about 1-2mm off the rim bead before I noticed and the top of the tire at full susp compression was hitting the inner fender above that stopping travel slightly. Again this is a 295/35/17 slightly stretched on a 11.5 +63. I'm running -3 camber. If you run less camber it will give you a little more inner clearance but not enough to add another 10mm you need to put your where i'm at, minus the banging in I had to do. Your best bet is to go with a +45-50. What ever that puts you outside the fender is the amount of over fender width you will need, which by my rough est is 25-30mm and this is not giving you any extra, its going to be spitting hairs. There is a thread rolling around of all the details/things to consider of my fitment and calculations of the 295/35/17 kuhmo XS if your interested, most of which I have articulated here already. Since your running over fenders, all that pertains to you is inner clearance/offset. I had to make this work within the outside fender as well since that was my goal.