Originally Posted by cvik
The only air compressors that I have ever seen are @ scuba shops that dry the air before filling a tank & they cost thousands of dollars.
Air dryers are a commom addition to almost any commercial compressor. There are several different styles. Prices for refrigerated units can run into the thousands while a desicant style dryer can cost as little as $50.00.
I use a desicant style on both the compressor in the shop and the one that stays in the motorhome. They keep the air dry enough that there has never been a problem with the tire balancing powder clumping.
As for the shop "incorrectly installing the valve stems" I'll bet the replaced the originals with the exact same stems in the exact same orientation. Every time we've bought new tires the stems have been replaced. The stems on the outer duals always face inward. While they are difficult to get at they can be filled and checked using the dual foot gauge and chuck.
Almost all outer duals have inward facing valve stems. Original production cost and installation is minimized by using a single style valve stem on all tires. By using a single style there is no concern that a tire will be installed in the wrong position. Most RV dealers install valve extensions on the inner duals so the customer doesn't have to remove the outer wheel (or a wheel cover) to access the valve stem.
If you feel the stems aren't accessible go back to the dealer and ask them to check the tire pressure in ALL the tires. I would ask to observe the process so you can do it by yourself in the future. If they can't do it on the outer duals it will certainly make them aware that they have made a mistake. At that point I would ask them to correct it. If they can check all the pressures easily I would ask what type of gauge and air chuck they use, then purchase those items for future use..