Ontario- Effecting trucks, truck-trailer combinations, and some specialty combinations. Such vehicles manufactured after June 2011 must be built to SPIF standards as contained in the regulation or operate at significantly reduced weights.

The Proviso Plus P300

- The Proviso Plus P300 can be used on most walking beam, air, and spring suspensions.

- The P300 is designed to lower the lift axle weight to improve steering. It does this by measuring the weight on the steer axle and maintaining the minimum weight ratio with the other axles.

• Frequently Asked Questions
• Simple Trouble Shooting
• P300 Sales Brochure

• P300 User Manual in English

• P300User Manual in French

• P300 Warranty in English

• P300 Warranty in French



• Monitors the steer axle weight and reduces the lift axle weight when needed.

• Fully SPIF Compliant. Great for schedule 21 and 23 trucks.
• Easy computer set up and calibration
• Internal temperature sensor and heater system to prevent freezing.
• Eliminates the driver stopping the vehicle to manually lower/ lift the axle.
• Low cost system kit with enclosure and Pneumatics built in for maximum savings
• Reduce wear & tear on tires & axles

• In-Cab Weight Display, including axle weights and front percentage

• Automatically lifts and lowers  the self-steeing lift axle according to weight
• Lifts the self steer lift axle when reversing.
• 4-way flasher weight distribution under 60KM/H
• Built in Internal air pressure sensors to monitor suspension.
• Built in pneumatics for controlling a lift axle
• Manual Override to lift the axle


The Proviso Plus™ P300 is an on-board scale system with lift axle control. The P300 will lift and lower the axle automatically based on the load condition of the truck. The P300 will also regulate the pressure on the lift axle to maintain compliance with Ontario's SPIF regulations.

The P300 will reduce the lift axle weight when the front axle weight is reduced below the SPIF regulate minimum. This reduction will help regain traction and streering.