yes, clean the inside of your rims.

built up brake dust will eventually require their own set of balancing weights when you get new tires.

also, if the inside of the rim is clean and your wheel wieghts aren't taped down, then you can see if one of those weights falls off and would explain why your wheels out of balance...

i also clean mine looking for stress cracks and the surface must be clean when i do a penetration test on them...