Protecting Your Tire Valves with R. Low
Most off-roaders have encountered a rock or branch that meets the valve stem in the rim, in such a way as to allow all the air out of the tire. If the valve stem is destroyed or pulled out of the rim, there is a much bigger problem.
Some may have the ability to remove the tire or collapse it enough to introduce a valve stem into the rim. This works. But a new stem is the better choice here as it won't be brittle with age or damaged. It is still a time consuming process when in less than ideal and uncontaminated surroundings. Still a pain in the butt though! There are ways to prevent or severely diminish this event. One way is to attempt to bully any rock or branch out of the way. Weld a piece of pipe over the hole in such a way that the valve cannot be compromised. Follow the hyperlink to see an artist rendition of how this works. This can be done by any competent welder with access to a die grinder. Another way is to install metal stems that are not flexible (like the one pictured to the right). The hope here is that the rock or branch will then slide past without damaging the valve. Could happen.
Another solution is to obtain shorter rubber valves, like from a wheelbarrow tire, that are just long enough to hold the valve cap. These come in metal also.
Hot Rodders have long used a 'flush' valve. The idea may have been to eliminate the shadow the stem throws on the deep chrome finished fancy wheels they admire. The system is close to the idea discussed above, however the valve body is completely enclosed inside the tire. Only a disc the size of a dime is visible in the rim. These require a special extension to swell up your aired down boots. They do not lend themselves to quick air down devices very well. They are costly and require that they be installed on a flat surface for the best seal and good results. There after, you may remove the dime shaped cap with a coin. There is little chance that a branch or rock can damage them. If they are placed against the disc of the rim they will be about as safe as it gets.
In the past, Off Roaders have tried moving the valve stem inboard in the rim so that the vulnerability of the stem is reduced. This requires drilling a hole and inserting a new valve stem next to the disc of the wheel. If you have reversible wheels this can allow you to have better access to both sides of the rim when airing up or down. Some leave the valve on both sides of the rim. Others get the unused hole welded up to seal the rim again and allow only one valve in the rim. Click though the photo to the left and you will see the weld within the red circle. Old timers may remember the bright engineering idea that cars had where the spare was provided with two valves, one to air up the space saver spare and the other to air it down again after use. It went the way of the Edsel, but this application should reassure you that you can safely run with two valves in one rim - provided your caliper doesn't remove it after the reversal has been accomplished... seen that too... embarrassing like an open fly in public.
The cost of this protecting your valves can vary but a guide could be my costs, encountered when doing some of the above. Cost of flush valves in hand
Cost of metal valves in hand
Cost of rubber valves in hand
Cost of welded ring (welding shop)
Cost of sealing unused hole (welding shop)
Cost of drilling a new hole
These costs do not include removing the tire from the rim and re-installing / balancing it. If you can remove tires and bring the rims to the welder already prepped, the above prices may be very close. It is conceivable that anyone who can grind, weld, drill holes and also remove the tires from the rims could do everything but balance the wheels on their own, in the back yard.
Before trying any of this, the disclaimer is: Talk to your local DOT enforcement people. If they say you can only run on the trails with this arrangement, do us all a favor and follow their advice... Remember Moab and the bead locks? Above all, keep the rubber side down. R. Low Santa Fe, NM