Tire Pressure Calculator

Most semi truck tires run between 90-120 PSI depending on position, load, and tire size. Steer tires typically need 100-120 PSI for proper handling, while drive and trailer tires run 90-110 PSI. The correct pressure depends on the actual load each tire carries — check the tire manufacturer's load/inflation table for exact recommendations.

Tire pressure changes approximately 2 PSI for every 10 degrees Fahrenheit change in ambient temperature. In cold weather, pressure drops — so a tire inflated to 100 PSI at 70°F will read about 90 PSI at 20°F. Always check and set pressure when tires are cold (before driving or after sitting 3+ hours). Running in hot weather naturally increases pressure.

Under-inflated tires increase rolling resistance, which directly burns more fuel. Research shows approximately 1% more fuel consumption for every 10 PSI below the recommended pressure. For a truck running 120,000 miles per year at 6.5 MPG and $3.80/gallon, running 15 PSI low could cost an extra $1,000+ per year in fuel alone.

Check tire pressure at minimum during every pre-trip inspection — ideally with a calibrated gauge, not just a thump test. The FMCSA requires drivers to inspect tires during pre-trip, but many fleets also use tire pressure monitoring systems (TPMS) for real-time alerts. Pressure should always be checked cold for accurate readings.

Steer tires typically run 5-10 PSI higher than drive tires because they handle the full steering load and must maintain precise responsiveness. Under-inflated steer tires cause poor handling, uneven wear, and increased stopping distance. Drive tires can run slightly lower since they share the load across a tandem axle and need traction rather than precision steering.