If your aluminum caps corroded, it was probably due to the material of the valve stem and not the alloy wheels. Our valve stems are aluminum, so I'm sure the caps are aluminum as well. If you use some other metal, make sure it is something compatible with aluminum or has a proper coating to prevent galvanic corrosion. Also, our caps have an o-ring to prevent contamination from getting into the stem. If you use something aftermarket, make sure they have an o-ring seal.