Dont run anything less than a 10 on the 500. I run an AMS Sand Snake MX 10-cup on my 19 inch rear. I've heard of people ripping off the paddles of an 8-cup on the 500, but have never tried an 8 on anything other than a 250 myself. You can check out my bike with the paddle tire in the gallery. Look for 25 on the number plate.