Tire size question

My rear-end was narrowed to accept common 15 x 10s with 4.5 bs.
The rear-end was removed, and then the wheel and tire assys were installed into the tubs at intended ride height. Then the body was dropped 1.5 inches to simulate a bump or corner. Then the assys were pushed inboard until the sidewalls hit the inner side of the tubs. Finally a tape-measure was stretched from mounting flange to flange.To this measurement I added 1/4 inch per side, for sidewall clearance.Then the rear end was narrowed to provide that measurement.
1/4 inch per side was not enough for aggressive cornering. 3/8 per side is mostly ok.I highly recommend 1/2 inch per side from sidewall to inner tub. To the spring can be less. But it is hard to corner aggressively with 325s. That is a whole new learning curve.
On the street,from a stop, I think 325s are more show than go. I did not notice any significant increase in traction on the streets that I drive. Remember I am a streeter and I usually pull the plug at the top of first gear which is 55 mph. Top of first-over is 68 mph.Top of second is about 85. And top of second-over is 110.Sometimes I might hit 68. They are a little harder to break loose at speed.
But they sure look nice in there.