Your backup plan in a flat-tire situation depends entirely on what your vehicle came with. Understanding your spare before you need it prevents surprises roadside — including discovering you have an inflation kit instead of a spare at all.
Full-size matching spare
What it is: a fifth tire and wheel, identical to your regular tires — or matching in size and load rating.
How long it lasts: indefinitely — the same life expectancy as your regular tires. Rotate it into the regular set every other rotation for even wear.
Speed limit: none specific — it is a regular tire.
Best for: trucks, SUVs, older vehicles. Anyone who regularly drives in remote areas where roadside service is not guaranteed.
Downside: heavy, takes cargo space. Many modern crossovers have eliminated it in favor of smaller solutions.
Temporary spare (donut spare)
What it is: a compact spare tire — narrower and smaller than regular tires — on a smaller steel wheel.
How long it lasts: 50–70 miles maximum before it must be replaced with a proper tire. Not intended for extended use.
Speed limit: 50 mph maximum. Exceeding this risks failure.
Best for: getting to a tire shop after a flat — nothing more.
Downside: cannot be used on an AWD vehicle for extended driving (the size mismatch stresses the drivetrain). Must be replaced as soon as possible.
Run-flat tires
What it is: tires with reinforced sidewalls that support the vehicle's weight even with zero air pressure, allowing continued driving at reduced speed for a limited distance.
How long it lasts after puncture: typically 50 miles at 50 mph or less — enough to reach a shop.
Best for: vehicles equipped with TPMS and run-flat OEM tires (BMW, Mini, Cadillac, Mercedes). The benefit is no spare needed — no storage space required.
Downside: run-flat tires cost 30–50% more than standard tires. After a puncture at zero pressure, the tire is typically destroyed (not repairable). Some run-flat punctures go unnoticed without TPMS — which is why TPMS is mandatory on run-flat vehicles.
Important: do not replace run-flat tires with standard tires on vehicles that have no spare — this leaves you with no backup option.
Tire inflation kits
What it is: a battery-powered air compressor and a can of tire sealant. No spare tire or wheel at all.
How long it lasts: sealant temporarily seals small punctures (under 1/4 inch). Works for slow-leak punctures; does not work for blowouts, sidewall damage, or large holes.
Speed limit after use: 50 mph maximum; get to a shop within 100 miles.
Best for: manufacturers trying to save cost and weight. Found on many modern compact cars and electric vehicles.
Downside: leaves foam sealant inside the tire that contaminates TPMS sensors and makes the tire non-repairable. Many shops charge $30–50 to clean the sealant out. Does not help with blowouts.
Frequently asked
Can I use a donut spare on an AWD vehicle?
Only for short distances at very low speed to get to a shop — not for highway driving. The donut's different diameter and rolling circumference can stress AWD differentials, couplings, and transfer cases with extended use. Replace the flat tire as quickly as possible.
What do I do if my car has no spare — just a tire kit?
Use the inflation kit for slow leaks to get to a tire shop. For blowouts or sidewall damage, call roadside assistance. Consider buying a compact spare and wheel that fits your vehicle as an aftermarket safety measure — check your vehicle's spare tire well dimensions.
Keep reading
Last updated 2026-06-27. General guidance only — confirm specifics with a local shop for your exact vehicle.