hotchkis leaf springs sitting too low :(
Tire and rim backspacing and clearance between tire and leaf spring.
You can get better backspacing rim and eliminate your issues.
We have a 4200 # big block car running BFG 255-60-15 tires on all 4 and we hit the curves about as hard as the tires can tolerate, so lots of heavy side loading.
This tire is definitely not a high performance tire, it has wimpy side walls and runs at 32 PSI so it does flex under side load quite a bit.
Now, we have exactly 1/2" clearance between the tire and spring. Occasionally if I lay into a long sweeping curve really hard, the tire will rub the springs.
I suggest you figure out what backspacing you need to put your actual tire exactly 3/4" from your leaf springs.
Run a 60 or 50 series tire and an 8" rim.
Getting max back spacing will optimize your outside spacing so you can run wider rim and still clear your quarter panel opening.