A tire that keeps going low is one of the most common and most annoying problems we see. You fill it Monday. By Thursday it's low again. You can't find a nail. You're not sure if it's the tire or the rim or the valve.
Here are the six causes we check, in order from most to least common.
The 6 Most Common Causes of a Slow Tire Leak
1. Small Puncture (Nail, Screw, Wire)
The most common cause. The object may be so small it's hard to see or hear. Even a thin wire from a steel-belted radial can cause a slow leak. Found via soapy water or submersion test.
2. Valve Stem Failure
Rubber valve stems crack and harden over time, especially in SoCal heat. The valve core inside can also loosen. Both cause leaks — both are cheap and easy to fix.
3. Bead Leak (Rim Corrosion)
Extremely common on vehicles over 5–7 years old in Southern California. The aluminum rim oxidizes at the bead seat, preventing a perfect seal. Looks like no leak, but air escapes where the tire meets the rim.
4. TPMS Sensor O-Ring
Each TPMS sensor has a rubber O-ring and grommet that seals around the sensor stem. These harden and crack over time. When they fail, air leaks around the sensor itself.
5. Cracked or Porous Rim
Alloy wheels can develop micro-cracks from impact damage or casting defects. Air seeps through the crack. In severe cases, the crack is visible — often in the spoke or near the bead seat.
6. Tire Porosity
Occasionally, a tire — especially an older or low-quality one — develops microscopic porosity in the rubber itself. Air seeps through the rubber evenly. No visible source. Usually shows up as bubbles all over during submersion test.
How We Find a Slow Leak
The gold standard is a full submersion test: we remove the wheel, submerge the inflated tire-and-wheel assembly in a water tank, and watch for bubbles. This finds leaks that soapy water misses — including bead leaks and micro-punctures.
For leaks we suspect are at the bead or valve, we can often diagnose without full submersion — a soapy water spray around the valve and bead perimeter will bubble up at the leak site within 30–60 seconds.
Why Bead Leaks Are So Common in Southern California
SoCal's dry heat and temperature swings accelerate oxidation on aluminum wheels. Vehicles that have been in the area for 5+ years — especially those driven near the coast where salt air is a factor — frequently develop bead corrosion. The white or gray oxidation at the bead seat prevents the tire from sealing perfectly against the rim.
The fix is straightforward: dismount the tire, wire-brush the bead seat on the rim, clean the tire bead, apply bead sealer, and remount. Most cases are resolved in under an hour.
Quick test at home: Mix dish soap with water in a spray bottle. Spray around the valve stem, around the bead where the tire meets the rim on both sides, and on the tread. Watch for bubbles for 30–60 seconds. This catches most leaks except deep punctures and porosity issues.
Walk-ins welcome at both Long Beach locations. If you've been adding air repeatedly and can't find the source, bring it in — we'll find it and fix it, and give you a written estimate before we do any work.
Frequently Asked Questions
Why does my tire keep losing air but I can't find a nail?
Nails are only one of six common causes of slow leaks. Valve stem failure, bead corrosion on the rim, a worn TPMS sensor O-ring, a micro-crack in the rim, or porosity in the tire itself can all cause air loss with no visible puncture. A proper submersion test will find the source.
Is it normal for tires to lose a little air over time?
Tires naturally lose 1-2 PSI per month through normal permeation through the rubber — this is normal. Losing more than that, or needing to add air every week or two, indicates a slow leak that needs to be found and fixed.
Can a bead leak be fixed without replacing the tire?
Yes. A bead leak is usually caused by corrosion on the rim at the seating surface. We clean the bead area on both the tire and rim, apply a bead sealer, and remount. In most cases this solves the problem without needing a new tire.
How do I tell if my valve stem is leaking?
Spray soapy water directly on the valve stem with the cap off. If you see bubbles, the valve core is leaking and needs to be replaced — a $5–10 fix. Valve stems themselves can also crack and need full replacement, especially on older rubber valve stems.
Will nitrogen inflate tires lose air slower than regular air?
Nitrogen molecules are slightly larger than oxygen molecules and permeate through rubber more slowly. Nitrogen-filled tires typically lose pressure a bit more slowly than air-filled ones, but it's not a cure for a slow leak — you still need to find and fix the source.
Have this problem right now? Ochoa's Tire Service is open 7 days a week — no appointment needed for most services.