If you can find any, 205/60/13 is the best size to run on a TR8. 185/70/13 was the stock size. Good 13 inch tires are getting impossible to find, that is the main reason everyone is buying 15" rims. You can run 205/50/15s which are an easy tire to source. All three of these tires have roughly the same rolling circumference, so your speedo shouldn't be affected by more than a couple MPHs. Most times, the 205s will fit without any rubbing issues, but occasionally you may need to trim a fender lip. Your speed rating should be sufficient for the speed your car is capable of doing, not that you will be going 130MPH often.