04/24/2012
Did you ever have a slight but aggravating tire-pressure loss on your aluminum alloy wheels? The reason is likely that the low pressure casting process with which the wheel was made has created small, micro-fine gas-entrapments that create air-passages from the tire-side to the weather-side of the wheel.
Even so good quality aluminum wheels are Helium leak tested in the factory, the small air passages may be opened as the wheel is exposed to loads and stresses.
If this is the case, removing the tire and valve stem, cleaning it and remounting it will not bring any positive results; even so most tire shops recommend this aforementioned procedure. There is one additional step that brings very likely the long awaited remedy to the problem. Remove the tire and the valve stem (as above), clean the tire side of the wheel very well, spray on an additional high quality clear coat layer, let it dry and remount valve stem and tire – voila! The pressure-loss problem is likely gone. If it reappears after a while, the clear coat layer may have been damaged at the leak area, and you can simply repeat the above steps.
There are other options: Replace the aluminum wheels with steel wheels - see this Concept Wheel. Steel wheels are made of rolled sheet metal and do not have such gas entrapments. Forged aluminum wheels, are more expensive, but due to the forging process they also do not have gas entrapments. For the layman’s eye it may be difficult to distinguish between a cast and forges aluminum wheel.