Free calculator
Trailer tandem weight from PSI
Pressure depends approximately linearly on load
1Calibration weighing
Tandem weight from a scale ticket and the trailer gauge reading at that moment
2Your gauge now
Weight below the suspension
Two axles, eight wheels and the brakes: about 3,000 lb on many dry vans
How it works
Below a trailer's air suspension, there are usually two axles, eight wheels, and the brakes. In our test, these parts weighed about 3,000 pounds when suspension pressure reached zero.
For this method, take a calibration weighing with the tandem load above 31,000 pounds while staying within the limits that apply to your equipment and route. Subtract the estimated 3,000 pounds below the suspension, then divide the difference by the pressure shown on your gauge. Now you have the weight change that corresponds to one psi.
Always check the applicable axle limits, bridge limits, road rules, and company procedures.
Watch the full explanation: Top Secrets of Load Control →
Drive axles and the tandem position
The Light version also helps calculate the drive axle suspension parameters using a similar formula with a different baseline for the drive axles. After calibration, you can use the app to estimate axle weights and find a tandem position for the load balance you need.