Question: 1965 Roadster Maximum Rear Tire Size?

[1965RRR]

Currently I am running BFG P215/70R15 T/A Radials on all 4 of my bolt-on knockoff wheels. I am looking to find the maximum size tire that I can install on the rear tires without rubbing. I have a reasonable amount of clearance now and "guesstimate" that P235s would fit.
Any info would be greatly appreciated.
Thanks, Andy

http://home.comcast.net/~instepdrive/

 

[groovyjay]

Here's 63 with 18" wheels. The rear tires are 275... Stock frame.