Cooling is one explanation, not an exclusion test.
A temperature drop can lower a gauge reading. A puncture, valve problem or rim-related leak can also cause loss. USTMA’s continuous-loss guidance calls for professional inspection when a tire continually requires reinflation. The linked guide explains the passenger/light-truck scope.
You cannot identify a leak location from a single PSI number, an online formula or a photo. The temperature estimate assumes no air loss; comparing a real tire with that assumption cannot prove the assumption is true.
Make two checks easier to compare.
- Identify the wheel position; keep front, rear and spare entries separate.
- Record the date, actual gauge reading and applicable specification.
- Note rested/recently driven condition, location and ambient temperature. Write down the gauge used.
- Record any adjustment, service or wheel-position change between checks.
- Take the record to a qualified service professional if the loss repeats.
Do not wait for a trend if a tire is damaged, rapidly losing pressure or the vehicle behaves abnormally. NHTSA advises consulting tire service for pressure-maintenance or performance problems.
Save, compare and download your observations.
The check sheet now saves a reviewed check on this browser only when you press Save this check locally. Enter a date first. After another check, it shows the numerical change from the previously saved check for the same wheel positions.
Both entries being marked cold does not prove equal tire-air temperature, gauge accuracy, load or absence of an intervening adjustment. Warm/unknown comparisons are labeled observations only. No loss rate or diagnosis is calculated. Export a CSV to keep a copy; clear the local records when no longer needed.
A record does not clear a tire for driving.
A matching placard value does not establish that a tire has no internal damage. Repeatedly adding air is not a substitute for assessment. The tools cannot certify repairability, roadworthiness or a safe remaining distance.
For a current warning, use the warning-pattern guide. For a low or high reading, start with the actual reading condition and vehicle specification.
Sources & scope
- USTMA Tire Care and Safety guide (©2018)
Passenger/light-truck care: repeated inflation loss, visual inspection limits, loading and valve caps. The PDF carries ©2018; its current revision date is not stated. The URL upload date is not the publication date.
- NHTSA TireWise
U.S. guidance: cold readings, vehicle placards, monthly checks and TPMS warning patterns.
- NASA Glenn: ideal-gas equation
Ideal-gas relationship and absolute temperature; supports the model, not tire-specific validation.
Primary sources checked November 5, 2026. This is not a vehicle-specific inspection.