Originally Posted by FBinNY

Weight limits for wheels aren't as much a safety issue, but a wheel life and serviceability issue. There's plenty of upside margin of error in any stated weight limit, but heavier riders, or riders that ride heavy won't see the life that lighter or better riders will get.

To give you some idea of wheel strength, I ride lightweight tubular tire wheels built with 15g spokes. I once pulled up behind a car stopped at a corner, only to have the driver throw it into reverse and start backing into a parking spot. His rear bumper caught by front wheel and climbed up onto it as we both rolled backward. I might not be typing, but he didn't have a limited slip differential, so it stopped when one of his rear wheels was of the ground, with 1/4 of the car supported on my wheel.

When I let him down, the wheel was 100% undamaged, so we know that even a light wheel can handle a static load of 750#s.