Brad, my understanding is that the Pro have the "best" compound.
That's my understanding too. The SS and R both have the same compound, but the R has a softer sidewall. The Pro is better than both, and is technically street legal, but has no rain grooves at all.
Oh, c'mon, it has TWO, TWO "rain grooves".
Perfectly fine for street driving.
'63 Dodge 330 11.19 @ 121 mph Pump gas, n/a, through the mufflers on street tires with 3.54's. 3,600 lbs. 10.01 @ 133mph with a 250 shot of nitrous an a splash of race gas. 1.36 60 ft. 3,700 lbs.
