Tire pressure light calculator
At what pressure does the tire pressure warning light come on? Enter the cold pressure on your door placard and your tire type to see the pressure the federal standard sets for your vehicle.
For Passenger (P-metric), standard load at a placard pressure of 35.0 psi, the light must come on within 20 minutes once any tire drops to 26.3 psi or lower, 8.8 psi below the placard; 25 percent below the placard pressure sets the threshold.
| Placard cold pressure | 35.0 psi | 241 kPa |
|---|---|---|
| 25 percent below placard | 26.3 psi | S4.2(a) |
| Table 1 minimum for this tire type | 20 psi | Table 1, column 3 |
| Light must come on at or below | 26.3 psi | 181 kPa |
The rule
FMVSS No. 138 requires the low tire pressure light to come on not more than 20 minutes after the pressure in one or more tires falls to 25 percent below the vehicle maker's recommended cold pressure, or to the minimum pressure in its Table 1 for that type of tire, whichever is higher. It applies to cars, SUVs, pickups and vans with a gross vehicle weight rating of 10,000 lb or less, except vehicles with dual wheels on an axle.
The light is a warning that a tire is significantly underinflated. It is not a reminder to set the right pressure: by the time it comes on, the tire is already about a quarter low. NHTSA's advice is to check the pressure at least once a month with the tires cold. See what the tire pressure light means.
Thresholds for common placard pressures
| Tire type | Placard | Light by | Set by |
|---|---|---|---|
| Passenger (P-metric), standard load | 30 psi | 22.5 psi | 25% below placard |
| Passenger (P-metric), standard load | 32 psi | 24.0 psi | 25% below placard |
| Passenger (P-metric), standard load | 33 psi | 24.8 psi | 25% below placard |
| Passenger (P-metric), standard load | 35 psi | 26.3 psi | 25% below placard |
| Passenger (P-metric), standard load | 36 psi | 27.0 psi | 25% below placard |
| Passenger (P-metric), standard load | 38 psi | 28.5 psi | 25% below placard |
| Passenger (P-metric), standard load | 40 psi | 30.0 psi | 25% below placard |
| Passenger (P-metric), standard load | 44 psi | 33.0 psi | 25% below placard |
| Passenger (P-metric), extra load | 35 psi | 26.3 psi | 25% below placard |
| Passenger (P-metric), extra load | 38 psi | 28.5 psi | 25% below placard |
| Passenger (P-metric), extra load | 41 psi | 30.8 psi | 25% below placard |
| Passenger (P-metric), extra load | 44 psi | 33.0 psi | 25% below placard |
| Passenger (P-metric), extra load | 49 psi | 36.8 psi | 25% below placard |
| Load range C | 45 psi | 33.8 psi | 25% below placard |
| Load range C | 50 psi | 37.5 psi | 25% below placard |
| Load range D | 50 psi | 37.5 psi | 25% below placard |
| Load range D | 55 psi | 41.3 psi | 25% below placard |
| Load range D | 60 psi | 45.0 psi | 25% below placard |
| Load range D | 65 psi | 48.8 psi | 25% below placard |
| Load range E | 45 psi | 35.0 psi | Table 1 minimum |
| Load range E | 50 psi | 37.5 psi | 25% below placard |
| Load range E | 60 psi | 45.0 psi | 25% below placard |
| Load range E | 65 psi | 48.8 psi | 25% below placard |
| Load range E | 70 psi | 52.5 psi | 25% below placard |
| Load range E | 80 psi | 60.0 psi | 25% below placard |
Limits of this calculator
The standard sets the latest point at which the light must come on; a vehicle maker can set its system to warn earlier. Table 1 names P-metric passenger tires and load ranges C, D and E. For a tire type it does not list, the calculator uses the 25 percent rule only. A flashing light that then stays on means a system fault, not low pressure.
Printed from https://tiresizecalc.net/tire-pressure-light-calculator/. Figures as published on 2026-11-01. The full working and the official sources are on that page.
Sources
- 49 CFR 571.138 - Standard No. 138; Tire pressure monitoring systems. National Highway Traffic Safety Administration (NHTSA), Code of Federal Regulations, annual edition (GovInfo). 2022-10-01. S2: vehicles covered. Retrieved 2026-11-01.
- 49 CFR 571.138 - Standard No. 138; Tire pressure monitoring systems. National Highway Traffic Safety Administration (NHTSA), Code of Federal Regulations, annual edition (GovInfo). 2022-10-01. S4.2(a) and Table 1: warning threshold and minimum activation pressure. Retrieved 2026-11-01.
- 49 CFR 571.138 - Standard No. 138; Tire pressure monitoring systems. National Highway Traffic Safety Administration (NHTSA), Code of Federal Regulations, annual edition (GovInfo). 2022-10-01. S4.4: malfunction indication. Retrieved 2026-11-01.
- Tires (Tire Safety). National Highway Traffic Safety Administration (NHTSA). Undated web page. TPMS and monthly pressure checks. Retrieved 2026-11-01.
- 49 CFR 571.110 - Standard No. 110; Tire selection and rims for motor vehicles with a GVWR of 4,536 kilograms (10,000 pounds) or less. National Highway Traffic Safety Administration (NHTSA), Code of Federal Regulations, annual edition (GovInfo). 2006-10-01. S4.3: cold pressure on the vehicle placard. Retrieved 2026-11-01.
- Computed by tiresizecalc.net from the cited formula. Sri Murugan Systems. Threshold = max(placard x 0.75, Table 1 minimum); 1 psi = 6.894757 kPa. Retrieved 2026-11-01.
Last reviewed 2026-11-01. The full source list, with dates and file checksums, is in How the numbers are calculated. To report an error, email contactus@tiresizecalc.net.