In Focus: Tire monitoring/inflation

Updated Apr 3, 2023

The cost of road calls, tire repairs and ruined casings can mess up the workday for both maintenance managers and finance officers. At the root of these problems is tire inflation maintenance, a sore subject for even the most dutiful driver because of the time and effort required.

To the rescue come tire inflation and monitoring systems. While some merely warn of low pressure or ease the walk-around inspection, others keep tires inflated and also warn the driver as soon as a leak develops.


The Airgo automatic tire inflation system is designed to check tire pressure at each individual valve stem so as not to extend tire pressure to the hub. If a hose should break, the tire will not go flat, and the system will maintain tire pressure in the remaining tires, the company says; to continue maintaining the other tires on the vehicle, simply disconnect the hose from the rotary union.

According to Airgo, the system has no moving parts within the hub area, so there is less chance of leaks in the lubrication compartment, reducing the possibility of pressurizing and/or damaging the hub seal. The vent/seal system offers venting to the atmosphere, keeping contaminants and water out of the hub cavity.

Airgo says the return on investment on its system often is compared to the cost of a single road call.

Commercial Vehicle Systems Group of Dana Corp.

The Dana SmartWave TPMS (Tire Pressure Management System) is designed to accurately measure the pressure and temperature of each tire constantly. It transmits data wirelessly to a receiver mounted on the tractor or truck and displays it in the cab. The system can be installed either as original equipment or aftermarket.

The Spicer TIMS (Tire Inflation and Monitor System) is designed to monitor and maintain proper tire pressure on trailers; it measures inflation pressure and notifies the operator when pressure drops to the desired setting. Its seals and lines remain unpressurized except when inflating, thus preventing premature seal failure, the company says.

The Spicer TPCS (Tire Pressure Control System) increases vehicle mobility over soft soil, sand or mud by adjusting tire pressure to the road conditions, according to the company; it uses a series of electropneumatic controls to feed air to the wheel ends as required.

Hendrickson TireMaax

There are now two TireMaax systems: the new TireMaax CP (for “constant pressure”) and the original TireMaax, now known as TireMaax EC (“electronic control”). Both systems are designed to keep trailer tires inflated and draw air from the trailer air system. TireMaax CP is a simple mechanical design, Hendrickson says, while the EC system provides full-system programming and monitoring.

The TireMaax CP is designed to check tire pressure continually without pressurizing the axles, and uses a pneumatic controller to pressurize the tires to a preset level. It has a signal light that informs the driver of tire or system leaks.

According to the company, both TireMaax units feature premium high-performance components, including bolt-in ball-bearing rotary unions; rugged, braided stainless-steel axle hoses; axle ventilation systems with patented axle filters; and seals designed to handle extreme temperature ranges.

Link Cat’s Eye

The Cat’s Eye system bolts to a lug bolt or the hub and connects to the air connections for the two duals. Its indicator shows a narrow slit when the tire is inflated properly, a slight opening as pressure drops 5 to 6 percent below the desired pressure, and a wide-open iris when the tire falls 10 percent below rated pressure. The driver needs to make only one air connection to inflate the tires, the company says, while check valves keep a tire with a leak from deflating the other in the dual set.


Each tire is equipped with a wheel module, which measures the tire inflation pressure using a pressure sensor. The sensor is designed to transmit pressure data regularly to an electronic control unit (ECU) via high-frequency radio signals.

The device’s ECU is mounted on the vehicle chassis and contains a built-in antenna to receive pressure data from all tires, even on articulated buses. Power is supplied by a lithium battery with a service life of more than five years.

According to the company, when switching on the ignition, the system informs the driver about pressure differences detected while the vehicle was stopped.


The MTIS (Meritor Tire Inflation System) by PSI (Pressure Systems International) is designed to add air to trailer tires automatically whenever a tire’s air pressure falls below specification. The system utilizes the air from the airbrake compressor.

A pressure protection valve is connected to the air supply and then connects to a control box mounted on the rear trailer axle cross member. The regulator is pre-calibrated to the specified tire air pressure. The only electrical component, located inside the control box, is a flow switch. When air flows through the flow switch at a rate that typically indicates a loss of air, a trailer-mounted light that the driver can see in his side mirror will illuminate.

Stemco Bat RF

The Bat RF Tire Pressure Monitoring System is designed to automate monitoring, collection and management of vehicle tire pressures using AirBat sensors and different forms of monitoring hardware.

The sensors include indicators that consist of an LED that blinks once per second when out of tolerance; these mount to the hubcap or lugnut, and their hoses connect to the tire valve stems.

Monitoring hardware available with the Bat RF includes a handheld portable reader, a fixed reader that might be mounted in a gate post, a mobile reader designed to interface with third-party vehicle tracking systems, and an In-Cab alert.