# Tire Valve Stem Replacement in Upland > A cracked valve stem leaks slowly. Route 66 Auto Repair in Upland replaces rubber stems and TPMS valve parts and leak-tests every wheel. Source: https://route66autorepairshop.com/tire-services/tire-valve-stem-replacement Updated: 2026-09-17 Business: Route 66 Auto Repair, 1775 W Foothill Blvd, Upland, CA 91786, (909) 608-7699 Hours: Monday to Friday 8 AM–5 PM, Saturday 8 AM–2 PM, Sunday closed **TLDR:** Cracked stems and **loose valve cores** cause slow leaks. We replace the stem or **TPMS seal kit** and water-test the wheel before it goes back on. The valve stem is the small part you fill the tire through, and it is a common source of slow leaks. Route 66 Auto Repair in Upland replaces cracked rubber stems, leaking valve cores and worn TPMS valve seals, then leak-tests the wheel. It is a small part that keeps air where it belongs through Upland's summer heat. ## What kind of valve stem does your wheel use? Most cars without direct TPMS use snap-in rubber stems. Heat and sunlight dry them out, and a bent or cracked base can leak where it passes through the rim. Direct TPMS wheels use a metal or rubber stem attached to the sensor, sealed with a grommet and a nut, and those seals and nuts wear and corrode. The valve core, the tiny spring valve inside the stem, can loosen or get dirt in its seat. The cap matters too: it keeps grit out of the core. A missing cap is an easy way to start a slow leak. ## Signs the stem is the problem - Bubbles at the valve when you dab soapy water on it. - Cracks at the base of a rubber stem when you bend it gently. - A hiss when the cap comes off that does not stop. - Green or white corrosion around a TPMS stem nut. ## Our valve stem replacement steps 1. **Confirm the leak:** The wheel is water-tested to be sure the stem, not the tread or bead, is leaking. 2. **Break the bead:** The tire is loosened from the rim so the old stem can be removed from inside. 3. **Fit the new stem or seal kit:** A new stem, or new TPMS grommet, nut and core, is installed and tightened to spec. 4. **Test and balance:** The tire is reinflated, water-tested and balanced before refitting. ## What's included - Leak test to confirm the source - New rubber stem or TPMS seal kit - New valve core and cap - Rebalance after the tire is reseated - Pressure set and TPMS reading checked ## Need-now or need-later? **Need now:** - A stem that leaks fast or is visibly split - A broken TPMS stem after a curb strike **Need later:** - Replacing aging stems at the next set of new tires - Adding missing valve caps ## How pricing and timing work Rubber stems are inexpensive parts; the labor is dismounting and remounting the tire. TPMS seal kits cost more, and a broken sensor adds a sensor line. New stems are fitted every time we do [tire mounting](https://route66autorepairshop.com/tire-services/tire-mounting), so it is often best to do both together. If the sensor itself is failing, see [tire pressure monitoring](https://route66autorepairshop.com/tire-services/tire-pressure-monitoring). For other leak sources, see [tire repair](https://route66autorepairshop.com/tire-services/tire-repair). AAA members save 10% on parts and labor, up to $75. ## Frequently asked questions ### Can a valve core leak on its own? Yes. A core can loosen or get debris in its seal. Sometimes tightening or replacing the core fixes the leak without replacing the whole stem. ### Do TPMS stems need service when I get new tires? Yes. Most sensor makers call for new seals, nuts and cores whenever the tire is changed. It prevents leaks around the sensor later. ### Are metal valve caps better? Plastic caps are fine for most cars. Some metal caps can corrode onto aluminum TPMS stems, so we fit the type the sensor maker recommends. --- Call (909) 608-7699 or visit https://route66autorepairshop.com/contact for a written estimate.