You'll kill r-comps a lot faster than street tires. The difference is the R-comps will cord pretty quickly unless you manage the tires. I've seen two guys cord a brand new Hoosier r6 in 6 sessions.
I agree with Purple, beginner and even intermediate drivers should stick with street tires. I see too many people blaming tires for understeer/oversteer issues on street tires when it's clearly a driver issue. Then they go to an R-comps to fix their skill issue which then makes that driver issue much more difficult to diagnose. AND they'll be a lot harder on the tires. You really should be very comfortable with knowing what the car is doing at the limit of grip otherwise it gets ugly really quick since you are carrying even more speed. Must also be smooth with the controls. I see too many hacks running r-comps and slicks.
Honestly, I'm maybe giving up a second per lap for 2-3 laps with my street tires every 20 min session. Otherwise, I'm running comparable times. Gotta ask yourself is it worth it? Tire changing, managing the tires, hard to drive in the rain, loading/unloading, etc. For me? Not worth it. I still pass plenty of cars on r-comps and slicks. FWIW, I run RS3s on my 330 and Dunlop Z1*'s on my M3 (just put on RS3s on my M3).
2013 F30 328i Melbourne Red
2011 E90 M3 Monte Carlo Blue
2004 E46 M3 Imola Red
Last edited by bigjae1976; 11-23-2012 at 10:05 AM.