Before the GTA rims that I have now, I had the stock Ttype rims on my car with 255s on the back and 235s on the front (BFGs). Did some research with a friend of mine that has been in the wheel and tire business forever (seems that way anyway). That was the biggest size that was recommended for those wheels. I wanted 265s like my brother had (he had different wheels).
The 84-85 Ttype wheels are very small in width, they are 15 x 6 if I remember right. I think these are the only TR wheels that are that slender, the GN wheels and 86-87 GN and Ttype wheels are 8" width (7" at the least). I thought it was a joke when I was shown the width.
With the 255s on the 15x6s it was a little too tall I think, like having 28" slicks (didnt help my 60 foots). I cant see an even wider tire on that wheel, I would think that it would be ballooning out the sides and not look right, and definately not be safe.
Just my 2 cents.