Ok I am guessing you are dropping to flat..correct?

Well then...STOP DROPPING TO FLAT!!!!

Even the best, biggest, burliest rim on the market (caugh caugh Sun Double Track) would be crying after doing a 5ft. to flat drop. So start finding/ building drops that have a transition, meaning the landing will be a nice slope. With the transition you are taking your downwards momentom and moving it forwards, there for not just smaking the ground.

Or you could start taking drops like trials riders, wich is just crazy what they can do.
15feet to flat, pfft no prob