Valve Stems

Valve stems are the cheapest part of a wheel and tire assembly and one of the most common causes of a slow leak. Rubber snap-in stems dry out, crack at the base where they flex, and fail from ozone and UV exposure long before the tire wears out. Replace them every time you mount a new tire.Rubber snap-in stems are standard for passenger applications and are rated to around 65 psi, which is fine for most cars and half-ton trucks. Metal clamp-in stems bolt through the wheel with a nut and a seal and are rated for much higher pressures, which is why they are correct for LT tires in load range E, for trailer tires, and for any application running above 65 psi. Metal stems are also the right choice for high-speed use since a long rubber stem can flex outward under centrifugal force.Two details that get missed: use the correct stem length for your wheel so that the valve clears the wheel face and is reachable with an air chuck, and always fit a valve cap. The cap is a secondary seal that keeps dirt and moisture out of the valve core, and a missing cap is a common cause of a corroded core that will not hold air.