I wanted to warn other owners about installing after-market metal valve stem caps. I replaced the OEM plastic caps with fancy metal caps that were made of a dissimilar metal than the valve stems. When I later went to check the air pressure in the tires I found one cap was frozen onto the valve stem. probably from moisture trapped in the threads. Penetrating oil didn't work. I had to cut off the metal cap using a Dremel tool taking great care not to damage the wheel and valve stem threads to avoid costing me the removal of the wheel, replacement of the valve stem and probably rebalancing the wheel. So my advice is to keep the OEM plastic caps. Just a warning and a word of advice to all other car enthusiasts that may be tempted to make the same mistake I made.