Airing Up The Viair 200P Portable CompressorWhether for emergency trail fixes or just airing up your tires once you're back on the pavement, it's a good idea to have a reliable air compressor on your rig. It makes you much more self-sufficient. Essentially, you have two choices: a compressor that is hard-mounted, typically under the hood; or a portable unit that you stow with the rest of your gear.
We recently had the opportunity to field test Viair's new 200P portable compressor, and we were surprised to find that, for it's size, it's a real workhorse. The company literature states that you can inflate a 33x12.50 tire from 15 psi to 30 psi in approximately three minutes, which we interpreted to mean closer to 3-1/2 to 4 minutes. As our XJ Cherokee runs 33x12.50s, we toted the 200P along with us on a recent trip to Johnson Valley, California, where we aired the tires down to 15 psi, 'wheeled for most of the day, and then pulled out a stopwatch to see if the real-world figures matched those supplied by Viair.
Surprisingly, the company's numbers were on the conservative side. The average time it took to inflate our tires from 15 psi to 30 psi was 2 minutes and 48 seconds. Not bad for a compressor that's small enough to fit inside a kid's lunchbox.
Aside from performing well, this 12-volt compressor is also well-built. The gearless, direct-drive motor is equipped with stainless steel valves, high-performance piston rings, and it is protected by an anodized aluminum housing. To be certain you don't accidentally burn it up, the compressor is also equipped with an automatic thermal overload protector. So if you run it for too long and it gets too hot, it will simply shut down before any damage is done.
The complete compressor kit comes with a 25-foot, heavy-duty hose that's equipped with a quick-connect fitting and a 60-psi gauge. And to make storing it as easy as possible, it all fits snugly inside a two-compartment canvas bag.
Airing DownKlune-V's Rapid Air-Down Valve StemPrimarily known for its extreme underdrive gearboxes, Klune-V has just introduced another innovative product: RAD, the rapid air-down valve stem. These stems are made of 100 percent stainless steel and are designed to perform all the regular functions of a regular stem, except where airing down is concerned.
The RAD valve stem features a knurled wheel with a heavy-duty rubber O-ring inside. This wheel screws down over the stem where it seats snugly against the rim. At the base of the stem is a series of holes that are covered by the O-ring. As the knurled wheel is turned counter-clockwise, the O-ring uncovers these holes, and the tire deflates - rapidly. The holes at the base of the stem allow more air to escape at a faster rate than can be accomplished by removing the core.
The engineers at Klune-V claim that these stems can take a 35x12.50 tire from 35 psi to 12 psi in 18 seconds. Needless to say, this got our attention. So after having the stems mounted on a set of American Racing rims outfitted with 35x12.50 Mickey Thompson Claws, we got the stopwatch and let the airing down begin.
Initially, we let the tire deflate for exactly 18 seconds and then measured air pressure with a gauge. It showed about 16 psi. After airing down the remaining three tires, our elapsed time showed that the RAD valve stems were taking the 35s from 35 psi to 12 psi in a little over 20 seconds. Not too shabby by any standard.
The only concern we had when we installed the RAD stems originally was that they might leak, but we've been running them on our CJ-7 for four months now, and at no point have we noticed any air loss.
This is a simple design that works well and will prove to be a real benefit to four-wheelers