no, i like them both for different reasons! they both have their pros and cons. actually just figured out the weight today.
RX-8 with 235/40 = 50lbs each
wheel = 23lbs, tire = 27lbs
MX-5 with 215/45 = 39lbs each
wheel = 17lbs, tire = 22lbs
traction is better with the RX-8s and 235s, but my car is faster with the MX-5s and 215s. i can definitely tell the difference...
yea that's a big difference in weight between the 2 so i can see how the MX-5's would allow you to get quicker times. RX-8's would probably be better if you were puttin down some serious power to the ground though. there's a guy around here who fully built his engine and he spins all the way through 3rd gear on the stock 215's