Just recently started modifying my wheels to gain some grip on extremely rough asphalt. I gave a set of wheels a few licks on the lathe and created deep under-cuts in the side walls, This made the lip much more pliable while retaining good rebound in the center section of the wheel. The result has been promising, better grip on acceleration and cornering on rough roads. Probably losing a little efficiency but the trade off is a good one for special conditions.
Customizing skate wheels is nothing new and is one of the ways many wheel companies test out ideas for new wheel molds. Would be interesting to hear some thoughts on this. Waste of time or one more area of fine tuning to get what we want from our boards?