Take some white shoe polish and put a 2 to 3 inch stripe on the tires, both of them, from the edge of the rims straight down to the outside edge of the tires and have someone video a run, do one for each side of the car . Look at those video in slow motion to see what the tires are really doing I can't tell if your rear tires are slicks, street tires, bias ply or radials What are they?