I currently have the MT Drag Radials on the back (255/50/16) and they are OK but they don't hold up at the track past 5 psi. I was looking at the 28x11.5x16 or the 28x12.5x16 ET Streets. Anyone ever try these? I'm pretty sure I would need a spacer for the 12.5" tires, not sure about the 11.5".