Valve Stem Extension and Stabilizer Guide
There are a limited number of extensions available for making it easier to check the air on your tires or add TPMS sensors to your valve stems. The extension you need will depend on what kind of wheel you have.
Nearly all outside duals come with the valve stems turned in. This can make it difficult to check the pressure and nearly impossible to add a TPMS sensor to the valve stem.
You can use a 180 degree extension to bring the valve stem back out on an aluminum wheel and a 135 degree extension will do the same for a steel wheel.
The shortest straight extension is 1 3/8 inches long. These are usually need on the 22.5 inch aluminum wheels on the front tires if the valve stem is too deep inside the wheel. A 45 degree extension is usually used for easier access on a front tire with a steel wheel with a cover or simulator. The easiest way to figure out what you need is to bend a straw at 45 or 90 degrees and see what works best.
The valve stems on the inside dual can be different lengths but, usually a four or five inch extension is long enough to extend the valve stem past the outside dual hand-hole. It’s easy to measure from the end of the valve stem to the outside hand-hole to see what length you need.
If you are adding an extension that is longer than three inches, you should stabilize it at the outside dual hand-hole so that it doesn’t bang against the wheel and compromise your valve stem. There are several stabilizer options available depending on your wheel type and size. Aluminum wheels will use rubber stabilizer and steel wheels with covers will use wire or metal.
A longer extension is sometimes needed on steel wheels to get past the chrome cover or simulator and, usually a flexible extension works better because of alignment problems with the hand-hole.
There are three kinds of stabilizers and the one you need will depend on what kind of wheels you have.
Aluminum wheels require a rubber stabilizer and there are several sizes. First, check to see what kind of aluminum wheel you have. Alcoa and Accuride are the two major ones but both Winebago and Tiffin use an aluminum wheel made in Taiwan. This information will be written somewhere on an aluminum wheel. Then measure the diameter of the hand-hole and check to see if the valve stem will come out at the center or will it come out off-center. From there you can look at the various rubber stabilizers and it should be clear which one will work for you.
Alcoa makes several hand-hole sizes and they are all angled. Accuride makes their wheels with just three round hand-hole sizes and straight sides so just measure the diameter and find the one you need.
Steel wheels, because of the thinner wheel cover, usually require a wire or metal stabilizer. These come in just three sizes but they are flexible so they can be bent to various sizes. The ends clamp on to the rim and the extension comes through the middle of the extension.
Sometimes the best solution for easier access to your valve stems is flexible extensions. Until recently, all Monaco, Holiday Rambler, and Safari motorhomes were sold with flexible extensions stabilized at an L-bracket that is riveted to the center hub cap. The extension on the outside dual comes back out the next hand-hole and the extension from the inside dual comes out on the opposite side of the hub. These extensions seem to last for about six to seven years and when you need to replace one, you should replace them all.
Flexible extensions are also a great option for any dual steel wheel with a chrome cover or simulator. In addition to an L-bracket, there are a couple different ways that these are stabilized. A bracket that attaches to the wheel cover is an easy-to-install option for many class C motorhomes.
It is not a good idea to add an extension to an extension.
Whenever you are adding an extension or a sensor to a valve stem, use some soapy water (spit also works) to check for air leaks.