If reflectors are required for your wheels, then I would suggest reflective tape wrapped from edge of braking surface to braking surface. You will need a quite a large width. If you are really picky about imbalance the put equal amount on opposing sides of rim. Depending on the profile of your rim the tape can almost be seen from any angle except for directly in line with the rear wheel. With white reflective tape its barely visble on a silver anodized rim during the daytime. Another bonus is that it is so light compared to plastic reflectors.