Thats cool man, looking at the photo posted above, they look brand new never been used.
What camber & roll center settings are you running?
Maybe try to make adjustments in camber to achieve an even patch across the slick's surface area.
What weight rear diff oil are you running?
Sometimes, too thick diff oils don't allow the rear to rotate around turns, causing the car to drag or break the tires loose.
You can also try changes in your droop settings, think weight transfer.
Also, what shores are you running?
You're in Texas correct, your temps are in the 40s to 60 degree range right now, yes?
It is possible you are running too hard or a summer shore rating.
More rear rubber is a given, real factory hot rods come with wider rear tires; it physics.
Let me know some more about your set-up, I'm more than to happy to try to help you.
Hope to race with you next October at our USGT Nationals at Mike's.
Thanks.