Whats a nice sized tire for a fastback Cuda

235/60/15 on 15x7 standard 4.25 BS Cragar SS. I have the 8 3/4 with the large bolt pattern truck axle conversion which brings the rims out a little on each side (compared to the stock small bolt axles). Just as an FYI, the front is 225/60/15 on same size rim.