Car Doctor Q&A: My Pontiac G6’s Tires are Losing Air

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Our thought is that a masked hoodlum is making off with this Pontiac G6 convertible owner’s precious tire air under cover of darkness, but Car Doctor John Paul has other, more far-fetched theories.

Q. I have a 2007 Pontiac G6 convertible that I use as a beach car. It is big and comfortable and fun to drive to the beach. The problem is that every week or so I need to add air to the two left side tires.

I have had the tires checked and the shop couldn’t find any nails, but did replace the valve stem insert, but still every two weeks I’m adding air to the left side tires.

Can I just fill the tires with tire sealer? The tires are only about two years old and in good shape but this is a pain and I’m afraid that one day the tire won’t just be low, but will go flat. What can I do?

A. If the tires are not to blame, then the issue is the wheels. Wheels can become corroded and leak around the rim where the tire’s bead seats.

Your Pontiac has alloy wheels that are prone to corrosion and parking the beach can only make matters worse. The abrasive nature of salt and sand can combine to corrode the wheels.

You can check for a bead leak yourself. Mix up a solution of car wash soap and water and slop some around the tire where it meets the edge of the wheel. If it’s leaking there, you’ll see it as the bubbles start to form.

It’s good to have a white crayon or a tire marking crayon handy so that you can mark the location. The tire will need to come off the rim and be cleaned using a fine cut sanding disc to remove any flaking clearcoat or aluminum corrosion.

Once the wheel is clean, the shop will apply a commercial bead sealer (a liquid rubber product), allow it to dry and reinstall the tire.

A word of caution, if the corroded area is more than 7 0r 8 inches along the rim, the rim should be replaced.

John Paul is senior manager of public affairs for AAA Northeast. A certified mechanic, Paul tests dozens of new cars each year and also hosts a radio show on AM 950