Finding a leak in your tire when there’s no obvious puncture

So you’re driving through Baltimore and out of nowhere, your Tire Pressure Monitoring System (TPMS) warning light comes on inside your instrument cluster.  Time to check the air in your tires.  You find one of your tires about 10psi lower than the others.  You check all around your tire but see no nails, screws, staples or any other foreign objects stuck through it.  Where could the air be leaking from?

air leaking from the bead of a tire

You can see where the air bubbles are forming over the leak where we sprayed a soapy water solution.

More and more, we are seeing tire leaks which are not caused by anything penetrating the tire, instead, they are due to a layer of corrosion that forms in the inside of the wheel where the tire seals.  This is called the “bead”.  Twice as common on aluminum wheels than steel models, this corrosion seems to be some form of oxidation.  Now that we’ve located the (not so) phantom tire leak, let’s dismount the tire.

air leaking from the bead of a tire

In this picture, the tire has been dismounted from the wheel and you can see the corrosion that has begun forming.

The only way to remedy this is to dismount the tire from the wheel and scrub this stuff off.  Only then will the tire stop leaking from it’s bead.  At Padonia Auto Service, we encounter this problem at least a couple times each week.  We are also equipped to diagnose other causes for a TPMS light such as a malfunctioning sensor.  We should also mention that the type of weather we get in Maryland varies and the extreme hot / cold variance we see through the seasons plays games with our tire pressure.  This is why it’s important to remember that if it’s winter time and your TPMS light comes on, check all of your tires, if they are all low, it’s unlikely that there’s a leak, rather just the harsh cold of a Maryland winter.