Spare Tire Pressure: How to Maintain Your Temporary Spare

Why spare tire pressure matters

A temporary spare tire is a safety device designed to get you to a repair shop. If it is underinflated, it cannot carry the vehicle's weight properly, which can cause overheating, wobbling, and even tire failure at highway speed. Overinflation is just as dangerous: it reduces the contact patch and makes the spare more vulnerable to impact damage.

Because temporary spares are smaller and stiffer than regular tires, they need a different pressure than your everyday tires. Running them at the wrong pressure can also affect vehicle handling, especially in emergency maneuvers. Keeping the spare at its specified pressure is a simple but critical part of your vehicle's maintenance.

Finding the correct pressure for your spare

The right pressure for your temporary spare is always listed in one of two places: on the vehicle's tire information placard (usually on the driver's side door jamb or inside the glove box) or on the sidewall of the spare tire itself. The vehicle placard gives the pressure recommended by the vehicle manufacturer, which is the number you should use.

Do not use the maximum cold inflation pressure printed on the tire's sidewall. That number is simply the highest pressure the tire can physically hold, not the operating pressure for your vehicle. The U.S. Department of Energy's fueleconomy.gov site also reminds drivers to rely on the vehicle placard, not the sidewall maximum, for regular tires. The same rule applies to spares.

If your vehicle is equipped with a full-size spare that matches the regular tires, use the same pressure as the other tires on that axle. If you are unsure, check the placard or the owner's manual.

• Check the vehicle placard first.
• If the placard is missing, look for the pressure molded into the spare sidewall (often near the size marking).
• For full-size spares, use the pressure listed for the front or rear axle where the spare is installed.

How to check and inflate your spare

Use a reliable tire pressure gauge and check the spare when the tire is cold, meaning the vehicle has not been driven for at least three hours. Many temporary spares are mounted in the trunk or under the vehicle, so they are already cold most of the time. Remove the valve cap, press the gauge firmly onto the valve stem, and read the pressure.

If the pressure is low, inflate to the specified value using an air compressor at a gas station or a portable unit. If you overinflate, let some air out by pressing the pin in the center of the valve stem with the back of the gauge or a small tool. After inflating, always re-check with the gauge to confirm the exact pressure.

It is wise to check the spare at the same time as your regular tires, at least once a month. Temporary spares can lose pressure more quickly because they are smaller and often have thinner rubber. A monthly check also lets you spot any visible damage, such as cracks or bulges, before you actually need the spare.

Types of temporary spares and their pressure rules

T-type spare tires are the most common temporary spares. They are covered under U.S. Federal Motor Vehicle Safety Standard No. 109 (49 CFR 571.109), which sets performance and labeling requirements for T-type spare tires. These tires are designed for temporary use at reduced speeds, and their maximum permissible inflation pressure is limited to specific values (32, 36, 40, or 60 psi). The vehicle manufacturer's recommended pressure for a T-type spare is usually on the placard, and it is often higher than your regular tires because the spare is smaller and carries a similar load.

Full-size spares are identical to the other tires on your vehicle and should be inflated to the normal cold inflation pressure for your vehicle. Some vehicles, especially SUVs and trucks, may come with a full-size spare that matches the original tires. In that case, rotate the spare into your regular rotation schedule if it is identical.

Non-pneumatic spare tires do not use air at all. They are covered under Standard No. 129 (49 CFR 571.129) and contain no gas or fluid to sustain the load. You cannot adjust their pressure; instead, you should inspect them for cracks, separation, or damage. If you have a non-pneumatic spare, there is no pressure to check, but you still need to verify it is securely mounted and free of deformities.

Maintenance and replacement considerations

Temporary spares have a limited service life. They are not designed for long distances or high speeds. Even if you never use it, the rubber compounds degrade over time and from temperature changes. Check the DOT manufacturing date on the sidewall; if the spare is more than 10 years old, it may be unsafe and should be replaced. Refer to our guide on tire age and dry rot for more details on aging.

Store the spare in a cool, dry place if it is not mounted on the vehicle. If it is mounted under the vehicle, make sure the carrier is not corroded and that the spare is not exposed to harsh road chemicals. Periodically lower it and inspect for damage. For storage advice, see our tire storage guide.

When you use a temporary spare, remember it is for emergency use only. Drive at or below the speed limit indicated on the sidewall, usually 50 mph (80 km/h). Replace the spare with a regular tire as soon as possible. If you need to buy a replacement tire, use our guides to find the right size and type for your vehicle, such as our best 16-inch tires or best 17-inch tires pages.

Driving and safety tips with a spare

Before installing a temporary spare, check that the correct lug nut torque is used when reattaching the wheel. Overtightening can damage the studs; under-tightening can cause the wheel to loosen. Our tire torque specs guide explains the proper procedure.

A spare tire is not a substitute for a proper repair. If you must drive on a spare, reduce your speed and avoid hard cornering, heavy braking, or carrying extra load. The temporary spare changes the vehicle's handling because it is smaller and has a different diameter. Some vehicles with all-wheel drive may require special care; see our article on AWD tire maintenance for more.

Your vehicle's tire pressure monitoring system (TPMS) may not monitor the spare. Under Federal Motor Vehicle Safety Standard No. 138, the TPMS only warns for the four road tires. If your spare is a temporary T-type, the TPMS will not alert you if it loses pressure. That is why a monthly manual check is essential.

What to pick for your use

Questions

What is the correct pressure for a temporary spare tire?

Use the pressure printed on your vehicle's tire information placard or on the sidewall of the spare tire itself. This is usually higher than your regular tires, often 60 psi for T-type spares. Never use the maximum pressure listed on the sidewall as your operating pressure.

How often should I check my spare tire pressure?

Check it at least once a month, along with your regular tires. Temporary spares lose air more quickly than standard tires. A monthly check ensures it is ready when you need it.

Can I use a temporary spare at highway speeds?

Temporary spares are designed for limited speeds, typically up to 50 mph (80 km/h). The speed limit is printed on the sidewall. Always follow that limit and avoid prolonged highway driving on a spare.

Does my TPMS warn me if the spare tire is low?

No. Under FMVSS 138, TPMS only monitors the four road tires. Temporary spares are not equipped with sensors, so you must manually check the spare pressure every month.