Flat tire in the driveway: what to do before you touch it

You came out to the car and one tire is sitting on its sidewall. The car has not moved, which is the good news, because a tire that went down while parked has almost certainly not been damaged by being driven on. That is the single biggest factor in whether it can be repaired.

Two things not to do in the next ten minutes.

Do not drive it to a shop. Driving on a flat destroys the tire in a few hundred yards. The sidewall folds under the rim and the inner liner tears, and a tire that was a twenty-minute puncture repair becomes a replacement. It can also damage the wheel itself, which is a far more expensive problem.

Do not just pump it up and carry on. Air in a tire that has a nail in it is a countdown, not a fix. If it went down overnight it will go down again, and the second time may be at 60 mph.

Work out what happened, without moving the car

Look at the tread first, the part that touches the road. Run your eyes over it slowly and look for a nail head, a screw head, or a bright metal fleck. Most punctures are in the tread, and most tread punctures are repairable.

Then look at the sidewall, the smooth part facing out. You are looking for a cut, a gouge, a bulge or a bubble. Anything in the sidewall is not repairable, ever, by anyone. The sidewall flexes constantly and no patch will hold there.

Then look at where the tire meets the wheel rim, the bead. A line of dirt or a visible gap there suggests the seal has failed rather than the tire being punctured. That is often fixable without a new tire.

If you find nothing at all, it may be the valve stem, which is the cheapest failure on the whole car, or a slow leak through corrosion on an older alloy wheel.

Whether it can be repaired

The rules here are not ours. The US Tire Manufacturers Association sets them and reputable shops follow them:

• The damage has to be in the tread area only.
• The puncture has to be no larger than a quarter of an inch, about 6mm.
• The tire has to come off the wheel so the inside can be inspected. Damage that looks minor outside is often worse within.
• A correct repair is a plug to fill the hole and a patch to seal the inner liner. A plug pushed in from the outside without removing the tire is not a proper repair, whatever it costs.

If all of those hold, a repair is the right answer and it is a fraction of the price of a tire.

When it is a replacement

• Anything in the sidewall or the shoulder, the curved part between tread and sidewall.
• A cut longer than a quarter inch.
• A bulge or bubble anywhere, which means the internal belt has separated.
• The tire was driven on while flat, even briefly.
• The tread is close to worn out anyway, in which case repairing it buys very little.

Why a driveway flat suits mobile service

Your car is immobile and it is on private ground. Those two facts together are the case for someone coming to you rather than you getting the car to a shop. The alternatives are a tow, or fitting the spare yourself and then driving on a temporary tire to a garage and waiting there.

We come to the car, take the wheel off, inspect the tire properly from the inside, and either repair it or fit a new one on the spot.

If you need the car before anyone can get there

The spare will move the car, with two caveats. A temporary spare, the narrow one, is usually limited to around 50 mph and a short distance, and its pressure is much higher than a road tire, often around 60 PSI. Check the label on the spare itself. Many cars built in the last decade have no spare at all, only a sealant kit, and sealant will not fix anything larger than a pinhole.

Questions people ask

• It went flat overnight but I cannot see a nail. What now? Very often a valve stem or a bead leak. Both are cheap and neither needs a new tire. Do not assume it is fine because you cannot see the cause.
• Can you repair it where the car is parked? Yes, where there is a legal, level, paved space with room to work around the car. A driveway is close to ideal.
• Is a plug on its own good enough? No. A correct repair means the tire comes off the wheel and gets a plug and a patch. A plug alone does not meet the standard.
• The tire is flat but I need the car in an hour. Fit the spare if you have one and stay under 50 mph, or wait for us. Do not drive on the flat.
• How much does a repair cost compared with a new tire? A repair is a small fraction of a tire. We tell you which one you need after the inspection, and the price before the work.
• It is a run-flat. Does any of this change? The car may still be driveable for a limited distance at reduced speed. Run-flats are repairable less often, and the rules are stricter. Tell us it is a run-flat when you book.