Valve stems and caps

What to check before you buy

• Replace any missing cap: a dirty valve can leak.
• On many cars with TPMS, the sensor is part of the valve stem: buy caps and cores made for TPMS valves.
• Rubber snap-in stems age with the tire: they are usually replaced with new tires.
• Caps with a rubber seal inside keep water out better than plain ones.

How to use it

1. Spray or brush soapy water on the valve, cap off.
2. Watch for bubbles for a few seconds.
3. Bubbles at the tip: tighten or replace the valve core with a valve core tool. Bubbles at the base: the stem needs a tire shop.
4. Inflate to the door sticker pressure and put the cap back.

Good to know

• The Schrader valve is named after August Schrader; his New York company made its first bicycle tire valve in 1891.^1,2
• A cap keeps dirt and water away from the valve core, and a cap with a rubber seal can hold air if the core leaks.^3,4,5
• On aluminum TPMS valve stems, use plastic or aluminum caps: a mismatched metal cap can corrode and seize onto the stem.^3,6,7
• Aluminum TPMS stems take nickel-plated valve cores, not plain brass ones, which corrode and can seize.^4,8

How we checked this page

Checked on October 16, 2026. We kept a fact only when two independent sources agree, and each one is numbered to its sources below. We never write a price: the listings come straight from eBay and show what sellers ask. This page was written with an AI assistant and checked against the sources below.