R compound. You may even be slower with the bigger street meat than with stock sizes depending on the track. On a track with a laptime of about 1:30 with stock street tires you can gain 2-3 seconds with the R tires (and 4-5 with race slicks BTW). And: They're much more consistent when you drive many laps. Be sure to put the right cold pressure in it, it's usualy much less than you're used to because R tires heat up more.
Once you go R compound, even with "smaller" sizes, you will never go back. Be prepared to stop much quicker, take several more miles per hour into all corners, and grin for at least 10-15 minutes after your first day with them. Good luck.
Stock size R compound, you will never regret it, except you can't drive that fast everyday :biggrin:
Remember to make sure your alignment is set to take advanatge of the R compound tires. They like lots of negative camber, if you use less toe they will still wear well too. I am running 2 degrees in front, 2.4 degrees in the rear, .1 degree toe out on front and .1 degree toe in on the rear. Great for RA-1's and work fine for my street tires. I am getting almost flat wear. :wink:
Definitely, the R compound tires. The Michelin Pilot Sport Cup is a good R compound tire. There are lots of other excellent R compound tires that come in the '91-93 stock sizes. I'm using the Toyo RA-1 and I really like them. You can find a list of dealers (including some in your country) in this previous topic. (Oh, and don't forget that you can fit your stock sized 15"/16" track tires inside the car and drive to the track on your street tires.)
When I first switched to using R compound tires on the track, I didn't notice any difference. I now know that's because I was accustomed to driving with street tires, and drove the same way. The past few years I've been using R compounds. I drove a recent event on street tires, and kept asking myself, "Why won't my car turn in and go where I steer it?" Of course, I knew the answer: I had gotten accustomed to the greater grip and responsiveness of the R compound tires, and was driving with street tires as though I expected them to respond the same way. They don't.