Hi Andy_MR2_Rev2
Have a read through this post from about halfway down page 1 where it will start discussing tyres.
In short though you have a couple of options.
The standard tyres sizes for the mr2 are as follows:
Fronts: 195/55/15
Rears: 225/50/15
However you can fit 20/55/15's on the front, which is what I have done and I find it makes the car much more stable, particularly at higher speeds, and has made my quick cornering much more controlled and precise due to the better grip.
The main 2 tyres makes your can get in the sizes are the Toyo Proxes T1R
(standard tyres used by Toyota on this car) or Falken Ziez ZE912/914's,.
I believe you can also get Yokohama AD08's in this size however they are more expensive and litle awkward to find.
Or you can splash out big and get road legal track tires from Toyo in the form of their R888's
Hope this is of help to you
edit: Also, I wouldn't go wider than 225 on the rear stock rims as they tend to get too much sidewall flex once you step up to 235 width and will make the rear end a bit more unstable when cornering.
