Plymouth duster rear suspension questions

IMO, by my results, you need the outboard spring in a turn to be nearly dead flat, to best absorb/distribute the weight coming from the other side. AND
I run 295/50-15s on 10s and the rims (wheels/whatever you wanna call them) are NOT wide enough for dual a purpose machine. To get good tire wear, I have to run 24psi, and in the turns the sidewalls roll over, and give me a lil rear-steer. I like it and it works for me, but I'm a streeter not a canyon-charger, so the tires are surviving.
275s are large enough for straight-line work, but my car likes to drift the rear out, so a lil more treadwidth keeps it from spinning out. Plus 295s look tough.