Rick's Free Auto Repair Advice

Why a tire keeps going flat

The four most common reasons tires keep going flat

Obviously, a tire puncture is the #1 reason why a tire keeps going flat. But if you’ve had the tire checked for punctures, here are three other common causes for air leaks in your tire/wheel.

Corrosion on the rim near the bead is a common cause of tire air leaks

Salt water and sand settle in the space where the tire bead meet the rim. Over time it starts to corrode the bead seating area. Once it starts, it spreads and causes a leak where your tire keeps going flat but you can’t find the leak. You can’t find the leak because once you drive on the tire, it heats up, expands and reseals. Your best bet at finding corrosion on the bead sealing area is to remove the tire.

If you find corrosion, use a wire wheel and sand paper to remove it. Treat the area with a rust converter and then re-paint it before reinstalling the tire. Some DIYers apply RTV of household silicone to the rim, but that won’t last long if you haven’t sanded off the rust and treated it before apply the silicone.

rim corrosion in bead area

Dirt in the valve core seal is a common cause of air leaks

They make valve stem caps for a reason; to keep dirt out of the valve core. If you’ve been sloppy about reinstalling the valve stem cap, dirt can enter the valve core and get embedded in the rubber valve stem seal. Sometimes the dirt gets so embedded you can’t get it out. Try replacing the valve core with a new one from any auto parts store. Use a valve core remover tool to remove and replace the core.

dirt in valve core seal causes tire to go flate

Valve stem leaks can cause air leaks

Rubber valve stems leak in two ways; corrosion on the rim where the valve stem seals and cuts from improper wheel cover installation. Wheel covers always have a cut-out to align with the valve stem. If you don’t install the cover properly, it can bend or cut the rubber valve stem, causing a leak that’s hard to find.

air leaks from valve stem
If you have TPMS sensors you can get leaks from the rubber seal-to-rim

Tire dealers often recommend a TPMS rebuild kit when you get new tires. If you passed on that and have tire that keeps going flat, chances are the rubber seal is leaking. Unfortunately, you have to remove the tire from the rim to rebuild the TPMS valve stem.

tpms valve stem
©, 2023 Rick Muscoplat

Posted on by Rick Muscoplat

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