There's a ton of threads on here to help but here's a short cliff's notes from what I've run in the past. Keep in mind, the reasoning your results may vary is truly dependent upon front coilover spring lengths are tire clearance.

18x10 + 35. Perfect square fitment for the evo 8/9 in my opinion. Just needs a roll in the rear and you could legitimately run anywhere from a 255 - 285 mm tire all the way around

18x10.5 +30. Front fits just fine without the need for a spacer. Rear needs a MAJOR pull/roll. If you run the SSB rear trailing arms, there are guys getting away with just a roll with the 18x10.5 + 38. There's another thread in this forum where someone is trying to run an 18x11 (differing offsets) square. Looks like rear trailing arms are required. There's a MASSIVELY long thread about these on this forum.

18x11 +15 fits perfectly up front without a spacer. No way in hell this fits in the rear unless you like a ton of poke. Ran a 295mm A052 - granted there will be rubbing behind the tire most likely, depending upon your castor. I ran this with a 255/10" rear tire/wheel setup this past season.

That might be also a subject for discussions...I could argue that our DCT transmission is a manual transmission with electronic actuators that could change gears on its own too!

LOL. I think you just typed out the definition of an automatic transmission.

O.K., I know this is last year's thread (who's gonna start the 2022??), but my question is related to post #191. I get I can't run a multi-disc clutch (I have an ACT single so no problem). I'm looking to upgrade my brakes, Sooooo, if I want to do some SCCA sanctioned AX, can I run two-piece brake rotors? The Street Touring rules says they can be "Non-standard brake rotors" and "aluminium rotor hats are allowed". Makes me think I'm Gucci.
What's your take?

I'm hoping to start up another 2022 thread soon, once the 2022 rules are finalized!

Yes, you're able to run 2-piece - stock diameter rotors for STU. No worries there!

Are you expecting to see some changes for rules 2022? I haven't kept up with some of the changes since SM has been pretty stable.

Honestly, I don't know for certain if there are any proposed changes for STU going into 2022.

I am only hoping to hear some good news about multi disc clutches for SST trainy...not sure when though, since the letter was sent couple of months ago

Thanks for the info about brake upgrades!! I want to be able to start to mostly track the car this year--- don't want to cook the brakes, but don't want to get bumped out of SCCA STU class, if I decide to do one.
LV///R, I enjoy all your tire/wheel combo pics and info. It helps us alot!!!
Did you see the SCCA's, STAC is requesting member feedback about moving the Fiat Sypder from STU to STR?

I didn't see the request, but it makes sense. Don't know what the hack they were smoking when they placed a Miata with a different trim into a different class

It'll be interesting to see if you get any news about that for 2022!


No problem! I hear you there. I'm planning on double purposing this car for SCCA Solo, but also the possibility of Gridlife Time Attack - street class as well as competing with the MIDDIV SCCA Time trials at local tracks to the midwest.

Glad to help with the wheel/tire combo pics in this thread. I've gained a lot of knowledge from members on here so I'm happy to contribute as well.

I did see that about the Fiata. I believe there's been a handful of people who wrote in about the classing of the Fiata. IT was discussed further up in this thread as well.

Also, a further, in depth discussion about the possible Fiata switch here: RoadRaceAutox.com

Thanks for update. My letter didn't make into this one, but it looks like it might be in the next one. Here is what I got for where the letter is right now:
Letter #31607 has been reviewed by the SEB.Your letter is waiting to be posted in the next Fastrack, which will be available on the 20th of this month.

Stock diameter *and* stock thickness I believe (to avoid those Girodisc ultralite things)

edit: 14.6.A

I suspect you might not like the response.