All-terrain vehicles use relatively low tire pressures for added traction. Occasionally, even at this low pressure, ATV tires will develop slow leaks. A slowly leaking ATV tire may lose a pound or two of air over a period of weeks. You can repair these slow leaks either as a do-it-yourself project or by taking the tire to an ATV or tire-repair facility. The first step for the do-it-yourselfer, often the most difficult step, is to find the exact location of the leak.
Examine the tire tread and sidewalls for any indication of puncture, cracking or tread separation. You can patch a puncture to the tread; but you usually must replace tires with punctured or damaged sidewalls. If there is no visible damage to the tread or sidewalls, proceed to the next step.
Unscrew the valve stem cover and determine whether the valve stem is leaking. Spray a small amount of soapy water over the valve stem. If you see bubbles, the valve stem is leaking. If you do not see bubbles, skip to Step 4.
Use the pointed end of a valve stem tool to let the pressure out of the tire. Then insert the wrench end of the valve stem tool into the valve stem, and tighten the stem if loose. If the stem does not appear loose, remove the stem and replace it with a new one. Replacement valve stems are available at most auto parts and tire stores, and most tire stores will replace the stem for a nominal charge.
Spread a film of soapy water around both inner and outer beads. The bead is the sealant applied between the rim and tire when the tire is mounted. If you see bubbles at the bead, you have identified the leak. Occasionally this leak is caused by a small grain of sand or dirt having worked its way into the bead. Brush the area vigorously with a stiff-bristled brush and allow the tire to sit for a few minutes. Test again with soapy water. If the brush removes the sand or dirt from the bead, the tire may seal itself after the particle is removed. Deflating and reinflating the tire may assist in this resealing.
If brushing does not fix the leaking bead, you may have a bent rim or damaged tire. Tire rim repairs are best performed by an experienced tire or ATV mechanic, as it is easy to destroy a rim through improper repairs. You need specialized tools to remove and remount an ATV tire; consider having an ATV or tire mechanic perform this task.
It can be difficult to find very slow leaks, and it may take several minutes to generate a single soap bubble. You can use shaving cream instead of soapy water; its higher density can make it easier to detect bubbles.
Valve stem leaks are among the most common problems with ATV tires. Always keep the valve stem cap screwed on to prevent dirt from entering the stem.
Tire sealants such as Green Slime are available. While these may seal some rim or valve problems, they are not generally recommended for such repairs. Tire sealants can damage tire rims, so follow the manufacturer's recommendations and warnings.