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When calibrated correctly with accurate reference weights on a certified scale, AirBagWeight achieves accuracy within 1-2%. Accuracy depends on calibration quality — the greater the difference between your empty and loaded calibration weights, the more accurate your results. For best accuracy, calibrate with a full load at or near maximum capacity.

AirBagWeight works with any truck that has air bag suspension. This includes most Class 7 and Class 8 trucks from all major manufacturers — Freightliner, Kenworth, Peterbilt, Volvo, International, and more. If your truck has air bags, AirBagWeight can work with it.

The sensor battery (CR1632) lasts approximately 1 year depending on driving mileage. In cold weather, the app may show a low battery warning — this is normal and the reading will return to normal when the temperature rises. When the battery is truly depleted, replace it with a standard CR1632 coin cell battery — see the Battery Replacement Guide on our Support page.

You need one sensor per leveling valve. Most tractor-trailer setups need just 2 sensors total: one for the drive axle and one for the trailer. The steer axle usually doesn't have air suspension — its weight is calculated based on the drive axle readings. Installation is DIY with a DOT Tee-fitting and Schrader valve.

Bluetooth covers most setups, but a sensor mounted at the very rear of the trailer may not reach the cab — especially with a load in between. Mount the sensor near the front of the trailer using a 1/4-inch air hose extension and you'll have a strong, reliable signal from the driver's seat.

Your weight data and calibration settings stay on your device. We only collect anonymous app usage analytics and crash reports (if you opt in) to improve the app — no personal data, no weight readings, no location tracking. You can disable analytics anytime in Settings. iCloud sync is optional and only syncs between your own Apple devices.

AirBagWeight is designed as a pre-check tool to help you avoid overweight fines, not as a legal replacement for certified scales. While the 1-2% accuracy is excellent for load monitoring, official DOT weigh stations use certified scales. Think of AirBagWeight as your early warning system.

AirBagWeight requires air bag suspension to work, as it measures air pressure to calculate weight. If your truck has leaf spring or other non-air suspension, this app won't be compatible. Most modern Class 7-8 trucks use air suspension.

The sensors communicate with your phone via Bluetooth. They report immediately whenever there is a change in PSI (e.g., when loading or unloading cargo). When the truck is parked and PSI is stable, sensors report every 2-3 minutes. If your truck has been sitting for a while, just open the app and wait a moment for the sensors to send their current data.

Yes — for accurate readings, always park on flat, level ground with parking brakes released on both the truck and trailer, and wheels chocked. Engaged brakes can affect air bag pressure and produce inaccurate readings. Slopes will also shift weight between axles and give incorrect results.