Spare tires explained: full-size, donut, run-flat or sealant kit

How common is each? Consumer Reports counted the setups on the cars it has tested since 2020. That is its own test fleet, not all U.S. sales, but it shows how far the full-size spare has fallen:

AAA has tracked the trend. In 2015 it found the share of vehicles sold without a spare had grown from 5% of 2006 models to 36% of 2015 models, with sealant kits and run-flats taking their place on 29 million vehicles. A 2017 count found 28% of 2017 models came without a spare as standard equipment. The two figures were measured differently, so they don’t show a decline, but either way it is a large share.

The reasons automakers give are weight, which helps fuel economy ratings, plus cargo space and cost. AAA’s engineers have argued the fuel savings are small. Packaging plays a part too: in the 2026 Subaru Forester Hybrid, for example, the hybrid battery sits where the spare used to go, so the car comes with a repair kit instead.

The flats haven’t gone away. AAA said in 2015 that it answers more than 4 million flat-tire calls a year, and that in 2016 it helped more than 450,000 members who had a flat and no spare.

Every owner’s manual we checked sets the same speed limit for a compact spare: 50 mph (80 km/h). Kia, Honda, Ford and Subaru state it as a limit; GM recommends it; Michelin gives the same advice and suggests avoiding highways where possible. None of the manuals gives a mileage limit. They say to replace the spare with a regular tire at the first opportunity, and Kia warns that continuous use could cause the spare to fail.

Compact spares usually take 60 psi, and federal rules require the words “Inflate to 420 kPa (60 psi)” on the sidewall of a spare with that maximum. Check its pressure right after you fit it. The manuals add a list of cautions worth knowing before you need them:

A sealant kit works by pumping sealant and air into the tire, then driving a short distance to spread the sealant before checking the pressure again. It only works on small punctures in the tread, ideally with the nail or screw still in place; Kia, Honda and Ford all say to leave it in. AAA found kits can’t handle a puncture whose object has fallen out, sidewall damage or a blowout, and each kit holds enough sealant for one tire.

The U.S. Tire Manufacturers Association says using the kit is not a repair, only a way to reach a service location, where the tire maker’s rules decide whether the tire can be repaired. Sealant can affect the tire pressure sensor: Ford requires the sensor and valve stem on that wheel to be replaced afterward, and Kia says to clean the sealant off the sensor. Sealant also expires, typically in four to eight years according to AAA, so check the date on the canister. Our puncture repair guide covers what happens at the shop.

Run-flat tires let automakers drop the spare altogether. After a puncture, Bridgestone and Continental say their run-flats can be driven about 50 miles at up to 50 mph; the U.S. Tire Manufacturers Association says limits are usually 50 mph and up to 100 miles, varying by tire. Because a run-flat looks normal even with no air in it, they require a working tire pressure monitoring system. Many can’t be repaired after running flat. See run-flat tires explained for the trade-offs.

Federal rules make automakers tell owners to check every tire monthly when cold, “including the spare”. Your tire pressure warning light almost certainly won’t do it for you: the federal requirement covers up to four tires, and GM’s Equinox manual notes its spare has no pressure sensor at all, so fitting it turns on the warning light. The spare’s correct pressure is on the door placard. See our tire pressure guide for how to check it.

Rubber ages whether the tire is used or not. GM and Ford say to replace the spare after six years even if it has never been used, and Goodyear says six years in service, spare included. Michelin’s outer limit is ten years from the date of manufacture. You can read a spare’s age from its DOT date code; our tire age guide shows how.

AAA suggests asking whether a spare is available when you buy a new car, rather than assuming one is included. Consumer Reports notes that many cars have room under the cargo floor for a compact spare even when they don’t come with one. If you add one later, a few checks matter: