The spare can lose air while doing absolutely nothing

Temporary spares spend most of their life hidden under a cargo floor, in a trunk well, or beneath a pickup or SUV. That makes them easy to forget during normal tire checks. Air pressure can drop over time even when the spare has never been driven on.

NHTSA recommends checking pressure in all tires, including spares. A compact spare may require substantially more pressure than the four road tires, so the door-jamb number you use for normal tires may not be the number for the temporary spare.

Make the spare part of the road-trip check

  1. 01
    Find the vehicle-specific spare specification

    Use the owner's manual, tire/loading information, spare-tire label, or other manufacturer-provided instruction. Many compact spares specify around 60 psi, but do not assume that number applies to yours.

  2. 02
    Measure pressure when the spare is cold

    Use a gauge that can comfortably read the required range. Add air to the specified cold pressure if the tire is otherwise serviceable.

  3. 03
    Inspect age and visible condition

    Look for cracking, bulges, cuts, damage at the valve stem, or other deterioration. A never-used spare still ages.

  4. 04
    Put your hands on the tools

    Confirm the jack, lug wrench, wheel-lock key if equipped, jack handle, and any spare-release tool are actually present and accessible with the vehicle loaded.

  5. 05
    Read the temporary-use limits before you need them

    Know the vehicle-specific speed, distance, tire-chain, and axle-position restrictions so you are not learning them on a dark shoulder.

If the spare is low, do not stop at adding air

  • Ask why it lost pressure if the loss is large or repeats after inflation.
  • Inspect the valve and tread area rather than assuming storage alone explains the loss.
  • Check whether the tire is past the vehicle or tire manufacturer's recommended service life.
  • Make sure the spare wheel is not badly corroded or damaged where it mounts.
  • Recheck pressure periodically even if your TPMS does not monitor the spare.

Safety check

A properly inflated compact spare is still a temporary tire

Correct pressure does not remove the compact spare's operating limits. Follow the owner's manual for maximum speed, distance, tire-chain use, stability-system notes, and where the spare may be installed. Replace or repair the normal tire as soon as practical.

Three spare-tire situations that need different decisions

Correct pressure, good condition, within manufacturer guidance
Emergency temporary use according to the vehicle manual

Keep the trip conservative and restore the full-size tire as soon as practical.

Low pressure but no obvious damage
A spare that needs inflation and monitoring before it can be considered ready

A major or recurring pressure loss deserves a leak inspection instead of repeated top-offs.

Cracked, damaged, very old, or unable to hold pressure
A spare that should not be treated as reliable emergency equipment

Replace or professionally inspect it before relying on it for a highway trip.