FOLLOW THE BUBBLES AND CHECK THE VALVES TO FIND TIRE AIR LEAKS

Dear Car Talk:

I am Deepak, once of India and the U.S., and now living in Canada, eh.

I often lose air pressure only in the front right wheel. It usually happens when the outside temperature drops or rises all of a sudden. I have a 2015 Toyota RAV4 AWD. And yes, it is silver in case you need to know the color.

Thank you for bringing a pure joy to millions.

— Deepak

Thanks, Deepak. By the way, j-o-y is not how you spell “misery.” The good thing about tires is that there are a limited number of things that can cause them to leak. It’s a problem even I can usually solve.

Obviously, if you drive over a screw or nail, or otherwise puncture the tire itself, you’ll lose air. But that kind of tire injury usually results in a pretty constant loss of pressure, not an intermittent one.

The second way air can escape is from the bead, which is where the rubber at the inside edge of the tire pushes against the inside of wheel rim. That bead should seal airtight. If the wheel gets bent, for instance, from driving through a pothole the size of Saskatchewan, that can create space between the tire’s bead and the rim and allow air to seep out. And it could leak only under certain conditions, like when the tire flexes a particular way over bumps or on turns or when it’s parked in a specific position. Or the metal wheel itself can corrode over many years and make it impossible to create a tight seal against the rubber bead. Your car’s a little young for that, but since you live in Canada, maybe you’ve seen more than your share of road salt, eh? So it’s possible.

The third way tires tend to leak is from the valve stem. There’s a device called a Schrader valve inside that valve stem that lets air go in but not out. And if that’s failing, air can escape that way.

So here’s what you do, Deepak: Take your RAV4 to a recommended tire shop. They’ll fill your tire, take that wheel off the car and put it in a vat of water. It may take a little time, but if there’s air coming out, they’ll see the air bubbles and figure out where it’s coming from.

If they don’t see air coming out, it’s possible that in order for the leak to occur, the weight of the car has to be on the tire. If it won’t leak for them in the water, then I’d have them remove the tire from the wheel, clean up the inside of the rim in case there’s rust there, apply plenty of the cement that goes between the bead and the wheel and then remount the tire with a brand-new filler valve.

I’d say that’ll give you an 80% chance of solving the problem. If not, bring it back, have them remove the tire again and remount it on someone else’s car, Deepak. Good luck.