A slow leak in your tire can be hard to notice at first, especially if there is no obvious damage to the tire’s rubber or nail protruding through the hole you just made. While this may eventually lead to a flat tire, it does so gradually, as opposed to a very obvious blowout.
This type of problem can occur even with a new tire or vehicle but is also a very common repair that can sometimes be done at home. However, repairs at home are not always possible, especially in the case of rim damage.
Common Causes for Slow Tire Leaks
A slow tire leak is more than just a nuisance. A leak can lead to low tire pressure. Not to mention that prolonged driving on a tire with insufficient air pressure can lead to greater tire damage or even a dangerous burst.
If you’re experiencing a slow leak, here are some things to look for:
- A flat tire: It is a common misconception that a flat tire leads to an instant flat tire. In many cases, however, the object that caused the flat tire gets stuck in the tire and prevents the air from escaping quickly. As with all tire leaks, it is important not to ignore a flat tire. At some point, the object either wears out and/or works its way out of the tire. Related: How to run with a Flat tire?
- Wheel damage: Another common cause of slow tire leaks is damage in the area where the tire bead meets the rim. This type of damage is usually caused by the driver hitting the curb, taking a bump at high speed OR those dreaded potholes! The impact deforms the metal surface of the wheel, which can cause the tire to detach from the wheel’s mounting surface.
- Damage to the valve stem: The third most common cause of slow tire leaks is worn or damaged valve stems. Time, use, and contact with elements can cause your valve stems to wear out and cause leaks.
Related: How to Fix a Flat Tire?
A built-in tire pressure monitoring system, or TPMS, may alert you of lower pressure in one of your car’s tires as the leak will cause the PSI to drop. If your car does not have such a system, you may notice a change in the quality of the ride while driving.
A visual inspection when stopping can indicate that the tire is losing air (or gas for nitrogen-filled tires) and is starting to flat. However, before a repair can be done, the source of the slow leak must be found.
If a thorough inspection of a leaky tire, which will likely require removal from the vehicle, does not find a nail or hole, the slow leak may be caused by a pinhole in the tread or sidewall. But the tire shouldn’t be the problem.
The air valve stem may be leaking and need to be replaced, or the tire bead (where it meets the wheel) may not be properly sealed to the rim (a common problem in areas where road salt is used which can attack the metal surface of the rim).
Soap and water, or just water, can help identify the source of a slow leak before a repair. Mix liquid soap with water in a spray bottle and spray all parts of the tire tread, sidewalls, valve stem, and opening (with the cap removed) and along the rim on both sides with the soapy water until you find a point where bubbles start to build up to form.
Then the air escapes. This is easier with the wheel away from the car, but you may be able to find the leak without removing the wheel, especially at the front where turning the steering wheel exposes the inner sidewall somewhat.
Another way to find a leak is to remove the tire and wheel from the vehicle and soak them in a tub of water. Bubbles form at the leak. If the tub isn’t big enough to submerge the entire tire, ride sections one at a time.
Pinholes and small holes in the tread that cause a leak can be clogged or mended. Large punctures cannot do this, and minor damage to the sidewalls or shoulders (where the tread and sidewall meet) usually requires replacement with a new tire. Valve stems and inserts (the tiny valve itself in the hose) with leaks can also be replaced.
If the slow leak is due to the wheel not being fully seated on the tire, sometimes removing the tire and applying a bead sealer can stop the leak.
So, how to fix a slow leak in a car tire?
It is important that you have your tire diagnosed by a professionally trained tire store or mobile tire repair service as soon as possible. In the event of a flat tire, you may want to use a tire repair kit to keep the tire properly inflated until you can have it serviced. The leak should then be permanently repaired with a suitable tire repair consisting of a hardened rubber shaft and a repair unit.
If the leak is caused by a damaged valve, a trained tire technician can usually replace the valve at a minimal cost. However, in some cases, the tire may need to be replaced.
If the leak is from a damaged wheel, a tire technician may be able to reapply and reseal the tire with a bead sealer. However, if the wheel is severely damaged, you may need to replace the wheel yourself.