Schrader promotes the use of its service packs when servicing the TPMS during tire changes and rotations. The company said each time a clamp-in sensor is removed from the rim hole, the grommet, nut, nickel-plated core and cap should be replaced. Snap-in sensors also should have their valves replaced each time the sensor is removed from the rim hole.

The reasons service pack replacement is critically important, according to Schrader, include:

• Rubber grommets replace old seals that may have taken permanent compression set;

• The valve stem nut replaces the old nut which may have damaged threads caused by over-torqueing or other mistreatment;

• Nickel-plated valve cores are used to prevent galvanic corrosion between non-similar metals (brass and aluminum), causing a brass core to seize into an aluminum stem;

• The valve cap with seal prevents dirt and moisture from entering the sensor and also acts as a secondary pressure seal. Old valve caps may have a seal that is compressed set or missing; and

• The washer replaces the old washer, which may have been deformed during initial installation.