Last weekend I went for my first ride at a real motocross track. I was riding harder than I ever have before but I'm pretty much a novice so I don't think I was riding past the limits of the bike. However, the next day when I went to clean up my bike, I had two flat tires, really loose spokes and wobbly rims (I can't tell yet if they're bent). Ok, so I flat-landed a few big (at least they were big for me) jumps but are the stock rims really that weak? (Honda CRF250X). Are aftermarket rims pretty much a necessity for anyone who jumps? If so, which ones? Now the real mystery - I know that my tires were filled to 13psi the night before the ride. I just removed the wheels and filled up the tubes to find the punctures and there ARE NONE!!!! The valves are also fine but nonetheless, the tires were flat! How's that?