Flat tire and no spare: what to do now

If the car is parked somewhere safe, leave it there and have the tire dealt with where it stands. Do not drive on a flat tire to find a shop, because a few hundred yards on a deflated tire wrecks a tire that could have been repaired and can damage the wheel as well.

If there is a sealant kit in the trunk, read the next section before you use it. Sealant fixes less than people expect and can cost you the repair.

First, check what the car actually has

Lift the trunk floor. Most cars built in the last decade have one of three things.

An inflator and sealant kit. A small compressor and a bottle of liquid sealant. This is now the commonest arrangement in new cars, because it saves weight and boot space.

A temporary spare. The narrow wheel, often with a bright cover. If you have one, fit it, and read the label on the spare itself for its speed and distance limits before you drive. How far you can drive on a donut spare covers that properly.

Nothing at all. Some cars with run-flat tires carry neither, on the basis that the tires get you home. If yours is one, see EV and run-flat tires.

What a sealant kit can and cannot do

It can handle a nail-sized puncture in the tread, in a tire not yet flat to the rim, well enough to get the car moving at reduced speed.

It cannot do anything about:

• A sidewall cut or a bulge.
• A cut longer than a nail hole.
• A tire that has come off the bead, which is what usually happens once a tire is fully flat.
• A leaking valve stem, a bead leak or a corroded wheel. See tire losing air with no nail.
• A tire that has already been driven on flat.

Sealant is not a repair. It is a way of moving the car once. The bottles carry an expiry date, which is worth checking before you need it rather than after.

The cost people do not expect

Sealant coats the inside of the tire. A proper repair needs the tire off the wheel so the inner liner can be inspected and a patch bonded to it, and a liner covered in sealant has to be cleaned before anything sticks. Some shops decline the repair rather than deal with it. Sealant can also coat a TPMS sensor and stop it reading.

So there is a real trade-off. If you genuinely need to move the car right now and the damage is a small tread puncture, use the kit. If the car is parked at home or at work and can stay there for a few hours, do not use it, because you may be converting a repairable tire into a replacement for no reason.

The honest options

Have it fixed where it is. This is what mobile service exists for. We come to the car at home or at work, take the wheel off, inspect the tire from the inside, and either repair it or fit a tire we have supplied. No tow, no driving on a flat, no waiting in a shop.

A tow. Works, costs more than the tire usually does, and still leaves you without a car at the other end.

Roadside assistance. If you are stranded on a highway shoulder, that is the call to make. We are not an emergency roadside call-out service.

Whether it can be repaired at all

The rules come from the US Tire Manufacturers Association, and they decide this, not us:

• Tread area only. Nothing in the sidewall or shoulder.
• No larger than a quarter of an inch.
• The tire comes off the wheel for an internal inspection.
• A plug and a patch together. A plug pushed in from outside is not a repair.

A tire driven on while flat usually fails that inspection regardless of the original puncture, which is the whole reason for leaving the car where it is. Repair versus replace a tire sets out the decision, and mobile tire replacement cost covers the price side.

If you never want to be here again

A plug-in compressor with a gauge, kept in the trunk, is cheap and solves the far more common case of a tire that is low rather than destroyed. Checking pressures monthly against the placard in your door frame prevents more roadside flats than any kit.

Questions people ask

• My car has no spare. What do I do with a flat? Leave the car parked and have the tire repaired or replaced where it stands. Driving on a flat destroys the tire and can damage the wheel.
• Does tire sealant actually work? For a small tread puncture in a tire that is not flat to the rim, well enough to move the car at reduced speed. It does nothing for sidewall damage, bead leaks, valve stems or a tire already run flat.
• Will sealant stop my tire being repaired? It can. A proper repair needs a patch bonded to a clean inner liner, and sealant has to be cleaned off first. Some shops refuse the repair rather than do it.
• Can I buy a spare for a car that came without one? Sometimes. It depends on whether there is space in the floor and whether a jack and wrench are available for that vehicle. Ask before assuming.
• Is a flat tire an emergency? Only if you are stranded somewhere unsafe, in which case call roadside assistance. A car parked at home or at work is not an emergency and is the ideal case for a scheduled mobile visit.
• How long does a mobile repair take? A puncture repair is a short job once the wheel is off. The inspection that decides repair or replacement happens first, and we give you the price before any work starts.