Flat tire or slow leak? When it can be repaired and when it needs replacing

What to do right now

• If a tire goes flat while driving, hold the steering wheel firmly, ease off the gas and pull over somewhere safe. Avoid hard braking.
• Don’t keep driving on a flat. It can destroy the tire and damage the wheel within a short distance.
• If you see a nail or screw in the tread and the tire is still holding air, leave it in. Pulling it out can turn a slow leak into a flat.
• If you put on a compact spare, drive gently and keep to the speed and distance limits printed on it.

Repairable or not

• Usually repairable: a single puncture in the tread area, 1/4 inch (6 mm) or smaller, from a nail or screw.
• Not repairable: damage in the sidewall or the shoulder, a cut or tear, a hole larger than 1/4 inch, or a repair that would overlap an earlier one.
• Replace it if the tire was driven while flat or very low. The sidewall can be damaged inside even when the outside looks fine.
• Replace it if it has a bulge, exposed cords, or tread worn down to the wear bars.
• Run-flat and some performance tires have their own manufacturer rules for repair. Check your manual.

Why a plug alone is not enough

A plug pushed in from outside may stop the leak, but nobody has looked at the inside of the tire, and it does not seal the inner liner. The U.S. Tire Manufacturers Association says a repair must remove the tire from the wheel, inspect it for all damage, and use both a rubber stem (plug) to fill the hole and a patch to seal the liner. Sealant from a can can get you to a shop, but tell the technician you used it.

A slow leak with no nail in sight

• A leaking valve stem or valve core.
• A leak where the tire meets the wheel, often from corrosion or a bent rim after a pothole.
• A tiny puncture that is hard to see.
• Tire pressure also drops in cold weather, so a tire pressure light on a cold morning is not always a leak. Check it against the pressure on the sticker in the driver’s door jamb.

How we handle it here

• We find the leak, check where the damage is and whether the tire can be safely repaired. If it can’t, we tell you why.
• We repair punctures, install your spare, and check the tire pressures while the car is in.
• We give you the price before any work starts, and nothing is done without your approval.
• We are open 24 hours a day, 7 days a week. Call to check what help is available right now.