Hendrickson TIREMAAX PRO-LB Tire Inflation System

Quick Facts

Manufacturer: Hendrickson
Product Name: TIREMAAX PRO-LB
Product Type: Load-based automatic trailer tire-pressure control system
System Category: Tire inflation, pressure relief, equalization, and monitoring system
Primary Position: Trailer axles and wheel ends
Pressure Control: Automatically inflates and relieves tire pressure
Load Input: Trailer air-spring pressure
Dual-Tire Setting Range: 85 to 120 psi
Wide-Base Single Setting Range: 100 to 120 psi
Minimum Pressure Threshold: 75 psi for dual tires and 90 psi for wide-base single tires
Compatible Tire Arrangements: Dual and wide-base single configurations when properly specified
Common Suspension Compatibility: Selected Hendrickson INTRAAX, VANTRAAX, and ULTRAA-K systems
Air Supply: Trailer compressed-air reservoir
Driver Notification: Trailer-mounted indicator lamp
Primary Benefit: Adjusts tire pressure to changing axle loads instead of maintaining one fixed pressure under every loading condition

Overview

The Hendrickson TIREMAAX PRO-LB is an automatic trailer tire-pressure control system that changes tire pressure in response to axle load. Unlike a conventional inflation system that maintains one fixed target pressure, PRO-LB uses pressure from the trailer suspension’s air springs to estimate axle loading and adjust tire pressure accordingly.

The system can add air when pressure is too low, relieve excess pressure, equalize connected tires, and maintain a configured minimum threshold. This allows a trailer to operate with tire pressures better matched to loaded, partially loaded, and empty conditions.

PRO-LB builds on the capabilities of TIREMAAX PRO by adding load-based pressure adjustment. Its purpose is to help improve the tire contact patch, control irregular tread wear, support fuel efficiency, extend casing life, and reduce tire-related downtime.

Key Characteristics

Automatic trailer tire-pressure control
Load-based tire-pressure adjustment
Uses air-spring pressure to estimate axle load
Inflates tires when pressure is below the applicable target
Relieves pressure when it exceeds the applicable control range
Equalizes connected tire pressures
Maintains a configured minimum pressure threshold
Compensates for changing loads and operating conditions
Supports dual and wide-base single tire arrangements
Trailer-mounted warning indicator
Protective hubcap valves help isolate individual leaking tires
Integration with selected Hendrickson trailer suspensions and wheel ends

Major Components

TIREMAAX PRO-LB controller assembly
Controller enclosure and identification decal
Pressure regulator
Minimum-pressure adjustment mechanism
Controller supply valve
Trailer reservoir supply line
Air-spring signal line
Damping tank or signal-conditioning components where specified
Delivery air lines
Axle air passages or internal axle tubing
Spindle plugs and fittings
Rotary unions
Hubcaps with integral isolation valves
Flexible tire hoses
Tire valve-stem connections
Electrical harness
Trailer-mounted indicator lamp
Pressure test ports
Emergency air-supply port

System Type and Design

TIREMAAX PRO-LB is a load-responsive tire-pressure control system for air-suspended trailers. The controller receives clean, dry compressed air from the trailer reservoir and a separate pressure signal from the suspension air springs.

Because air-spring pressure changes with trailer loading, the controller can use that signal to vary the tire-pressure target. The system maintains a minimum tire pressure when the trailer is empty or lightly loaded and increases the target as axle load rises.

Air is routed from the controller through the axles and wheel ends to the tires. Rotary unions allow the stationary air supply to communicate with the rotating hubs and wheels.

How the Tire Inflation System Works

The trailer reservoir supplies compressed air to the PRO-LB controller. The controller compares its configured pressure relationship with the signal received from the suspension air springs.

When trailer loading increases, air-spring pressure rises. The controller responds by increasing the tire-pressure target. When the trailer is unloaded or lightly loaded, air-spring pressure falls and the controller reduces the target without allowing pressure to drop below the configured minimum threshold.

If tire pressure is below the applicable target, the controller supplies air through the axle and wheel-end plumbing. If pressure is excessive, the controller vents air until pressure returns to its intended operating range.

The trailer air reservoir must remain above the desired tire pressure because the controller cannot deliver more pressure than the available supply. The system also requires clean, dry trailer air for dependable operation.

Position and Function Within the Vehicle

TIREMAAX PRO-LB is installed on a commercial trailer and serves its tire and wheel-end assemblies. The controller is normally mounted beneath the trailer in a protected but serviceable location.

The system performs several functions:

Monitors the pressure relationship within the tire-delivery circuit
Uses suspension air pressure as an axle-load signal
Adds air to tires that fall below the applicable target
Relieves excess pressure under controlled conditions
Adjusts target pressure as trailer load changes
Equalizes connected tires
Protects unaffected tires from a leaking tire through hubcap isolation valves
Activates an indicator lamp when inflation or service attention is required
Helps maintain a more appropriate tire contact patch
Reduces the need for manual pressure changes between loaded and empty operation

Common Specifications

System Type: Load-based automatic trailer tire-pressure control system
Pressure Functions: Inflation, pressure relief, equalization, and load-based adjustment
Load Signal: Suspension air-spring pressure
Dual-Tire Setting Range: 85 to 120 psi
Wide-Base Single Setting Range: 100 to 120 psi
Dual-Tire Minimum Threshold: 75 psi
Wide-Base Single Minimum Threshold: 90 psi
Air Supply: Clean, dry compressed air from the trailer reservoir
Indicator: Trailer-mounted warning lamp
Tire Arrangements: Application-specific dual or wide-base single tires
Suspension Categories: Controller calibrated for the applicable Hendrickson suspension category
Primary Suspension Families: Selected INTRAAX, VANTRAAX, and ULTRAA-K models
Maximum Recommended Installation: Normally no more than two PRO-LB-controlled axles per vehicle combination without Hendrickson engineering approval

Pressure Settings and Operating Capacity

The selected cold tire pressure must satisfy the tire manufacturer’s requirements for the actual axle load. PRO-LB then changes the target within its calibrated range as the air-spring load signal changes.

Hendrickson identifies a setting range of 85 to 120 psi for dual-tire systems and 100 to 120 psi for wide-base single systems. The corresponding minimum-pressure thresholds are 75 psi for dual tires and 90 psi for wide-base single tires.

The controller lid decal identifies the applicable suspension category, minimum pressure, and cold tire pressure at the specified axle load. Those values must match the trailer’s suspension, tires, axle loading, and approved application.

Load-Based Pressure Adjustment

Commercial trailers can experience large differences between empty and fully loaded axle weights. Tires inflated for maximum load may operate at excessive pressure for their actual load when the trailer is empty or lightly loaded.

PRO-LB uses air-spring pressure to respond to this variation. As axle load rises, the system increases tire pressure. As axle load falls, it reduces pressure while maintaining the configured minimum threshold.

This load-based approach is intended to preserve a more appropriate tire contact patch, limit irregular wear during lightly loaded operation, and maintain sufficient pressure as payload increases.

Inflation, Relief, and Equalization

When tire pressure falls below the applicable target, PRO-LB routes reservoir air to the tires. The indicator lamp may illuminate while the system is actively correcting pressure.

If pressure rises above the allowable control range because of temperature, altitude, or reduced loading, the controller can vent excess air. Normal venting from the controller may therefore be part of system operation rather than evidence of a leak.

The controller typically keeps pressure below approximately 10 psi above the intended target, with Hendrickson noting that normal control may be approximately 5 to 7 psi above the target before relief occurs.

Air Supply, Controls, and Electrical Integration

The system receives compressed air from the trailer reservoir. Reservoir pressure must be greater than the required tire pressure, and the air supply must remain clean and dry.

The controller contains the regulation, load-sensing, minimum-pressure, delivery, and relief functions. An electrical harness connects the controller to a trailer-mounted indicator lamp that alerts the driver when the system is delivering air for an extended period or may require service.

If the indicator remains illuminated continuously for more than approximately ten minutes while the vehicle is operating, one or more tires may be low or the system may require inspection. Repeated cycling can indicate a slow leak in a tire or system line.

Installation and Calibration

Installation requires correct controller selection, suspension-category calibration, air-spring signal plumbing, axle preparation, wheel-end components, tire hoses, electrical wiring, and leak testing.

The controller must be matched to the suspension family and tire arrangement. Calibration and field verification require the Hendrickson PRO-LB field adjustment tool or another procedure specifically approved by Hendrickson.

During adjustment, the trailer reservoir should be fully charged, the parking brakes applied, and the wheels chocked. The technician verifies both the cold pressure at the specified axle-load signal and the minimum pressure for the empty or lightly loaded condition.

Trailer, Axle, and Wheel-End Compatibility

PRO-LB must be matched to the complete trailer, suspension, axle, wheel-end, and tire configuration. Compatibility depends on:

Trailer manufacturer and model
Suspension family and model
Suspension capacity and category
Axle model and spindle configuration
Number of controlled axles
Dual or wide-base single tires
Cold tire-pressure requirement
Tire load and inflation tables
Hubcap and rotary-union design
Wheel and valve-stem arrangement
Trailer air-reservoir capacity
Air-supply cleanliness and pressure
Electrical and indicator-lamp requirements
Original-equipment or approved retrofit availability

Common Applications

Dry van trailers
Refrigerated trailers
Flatbed trailers
Tank trailers
Moving-floor trailers
Drop-deck trailers
Specialized highway trailers
Trailers operating with highly variable payloads
Fleets accumulating significant empty miles
Applications using dual trailer tires
Applications using wide-base single trailer tires
Selected Hendrickson integrated suspension and axle systems

Advantages

Automatically responds to changing axle load
Adds air when tire pressure is below the applicable target
Relieves excessive tire pressure
Maintains a minimum pressure threshold
Reduces dependence on one fixed fully loaded pressure
Can improve tire contact under lightly loaded conditions
Helps reduce irregular tread wear
Supports longer tire and casing life
May improve fuel efficiency through better pressure control
Reduces manual pressure-adjustment requirements
Provides a visible warning indicator
Integrates with selected Hendrickson suspension and wheel-end systems

Limitations or Considerations

Requires an air-suspended trailer
Requires clean, dry compressed air
Cannot supply pressure above available reservoir pressure
Must be calibrated for the specific suspension and tire arrangement
Not every Hendrickson suspension model accepts PRO-LB
Thirty-thousand-pound-capacity systems may be excluded
Installation on more than two axles per vehicle combination is generally not advised without engineering review
Air lines, hoses, seals, and rotary unions add service points
Normal controller venting may be mistaken for a system leak
The indicator lamp does not identify the exact leaking tire
Manual tire inspections and pressure checks remain necessary
The system cannot repair a damaged tire or replace proper tire maintenance

Driver and Operator Experience

During normal operation, the system works automatically without requiring the driver to change tire pressure after each change in payload. The driver may occasionally hear air exhausting from the controller as it relieves pressure.

The indicator lamp may illuminate temporarily when the system is adding air, particularly during startup after tires have cooled. A lamp that remains on for an extended period or cycles repeatedly requires investigation.

Drivers must continue conducting normal pre-trip and post-trip tire inspections. PRO-LB does not identify tread damage, exposed cords, sidewall cuts, loose wheel nuts, damaged wheels, or every type of rapid tire failure.

Sensor Programming and Tire-Position Assignment

PRO-LB is primarily a pneumatic pressure-control system rather than a wheel-position TPMS requiring individual electronic sensor assignment. Its standard warning system monitors system activity rather than displaying a separate pressure reading for every tire.

If the trailer also uses an independent tire-pressure monitoring or telematics system, those sensors must be programmed and assigned according to that system’s instructions. Their pressure thresholds should be coordinated with PRO-LB’s changing load-based targets to avoid unnecessary alerts.

Inspection and Wear Points

Routine inspection should include:

Controller enclosure and mounting
Controller supply valve
Reservoir supply line
Air-spring signal line
Damping tank and related fittings
Axle supply lines
Spindle plugs and internal axle tubing
Rotary unions
Hubcaps and isolation valves
Flexible tire hoses
Valve-stem connections
Electrical harness and connectors
Indicator lamp operation
Controller test ports and vent
Signs of air leakage, abrasion, heat damage, or contamination

Maintenance and Ownership Notes

Check all tires manually during regular inspections
Confirm the controller supply valve remains open during normal operation
Inspect hoses for rubbing, cracking, and kinking
Check fittings and air lines for leakage
Inspect hubcaps and rotary unions
Test the trailer-mounted indicator lamp
Maintain the tractor and trailer air dryers and reservoirs
Drain moisture from air reservoirs as required
Verify pressure settings after controller service
Confirm suspension-category calibration
Inspect electrical wiring and connectors
Use genuine or approved replacement parts
Follow wheel-end service procedures that protect the inflation components
Consult Hendrickson before changing tire size or wheel arrangement

Common Tire-Inflation-System Problems

Indicator lamp remains illuminated: One or more tires may be low, the system may be supplying air continuously, reservoir pressure may be insufficient, or the system may require service.
Repeated indicator cycling: A slow tire leak, damaged hose, loose fitting, leaking rotary union, or other plumbing leak may be responsible.
System will not inflate tires: A closed supply valve, low reservoir pressure, restricted line, controller fault, blockage, or disconnected plumbing may prevent air delivery.
System will not relieve pressure: Incorrect calibration, controller contamination, damaged relief components, restricted plumbing, or an incorrect load signal may be responsible.
Incorrect load-based pressure: A leaking or restricted air-spring signal line, incorrect suspension category, calibration error, or suspension problem can affect the controller’s response.
One tire remains low: A closed or damaged hubcap valve, blocked hose, leaking tire, valve-stem problem, or failed wheel-end component may isolate that position.
Excessive controller venting: Normal pressure relief, incorrect adjustment, an excessive air-spring signal, or a controller fault may cause noticeable exhaust.
Contaminated controller: Moisture, oil, or debris from the trailer air system can interfere with regulation and valve operation.

Safety and Service Precautions

Chock the trailer wheels before beginning service
Apply the trailer parking brakes when instructed
Never work beneath a trailer supported only by a jack
Relieve system pressure before disconnecting pressurized lines
Wear eye protection when working with compressed air
Keep hands and tools clear of exhausting ports
Do not exceed approved tire or wheel pressure ratings
Do not assume the system makes a visibly damaged tire safe
Close the controller supply valve when isolating a significant system leak
Verify every tire has adequate pressure before returning the trailer to service
Use approved procedures during hub and wheel-end service
Follow Hendrickson, tire-manufacturer, trailer-manufacturer, and fleet instructions

Identification Information

System information is located on the controller enclosure, lid decal, suspension identification tag, axle tags, and individual components. Record the following information before ordering parts or adjusting the system:

Trailer manufacturer, model, and VIN
Hendrickson suspension family and model
Suspension category
Axle model and serial information
TIREMAAX system type
Controller assembly part number
Minimum tire-pressure setting
Cold tire pressure at the specified axle load
Dual or wide-base single configuration
Hubcap and rotary-union part numbers
Hose and fitting configuration
Indicator-lamp and wiring information
Tire size, load range, and required pressure

Buying Considerations

Confirm that the trailer uses a compatible air suspension
Identify the exact suspension model and category
Verify axle and spindle compatibility
Choose dual or wide-base single configuration
Confirm the tire manufacturer’s load and pressure requirements
Verify the desired cold and minimum pressure settings
Check trailer air-reservoir capacity and condition
Confirm the number of axles to be controlled
Determine original-equipment or retrofit availability
Verify hubcap and wheel-end compatibility
Confirm indicator-lamp and electrical requirements
Review installation labor and axle-preparation requirements
Check replacement-parts and service-tool availability
Use an installer familiar with trailer tire-inflation systems

Variants and Configurations

Dual-tire configurations
Wide-base single-tire configurations
Different cold-pressure settings
Different minimum-pressure thresholds
Suspension Category A calibration
Suspension Category B calibration
Suspension Category C calibration
INTRAAX-compatible systems
VANTRAAX-compatible systems
ULTRAA-K-compatible systems
Different hubcap and rotary-union arrangements
Original-equipment installations
Approved retrofit configurations
Integration with selected HXL wheel-end packages

System availability depends on suspension model, axle, capacity, wheel end, tire arrangement, and trailer specification. The complete application should be verified with Hendrickson before ordering.

Comparison to Similar Equipment

Compared with the Hendrickson TIREMAAX PRO Tire Inflation System, PRO-LB adds automatic load-based pressure adjustment. TIREMAAX PRO inflates, equalizes, and relieves pressure around a configured target, while PRO-LB changes its target according to the suspension load signal.

Compared with the Hendrickson TIREMAAX CP Tire Inflation System, PRO-LB provides pressure relief and load-based adjustment in addition to automatic inflation.

Compared with the Meritor Tire Inflation System, TIREMAAX PRO-LB uses Hendrickson’s suspension air-spring signal to vary tire pressure with axle load. The correct choice depends on trailer, axle, wheel-end, and fleet requirements.

Compared with the Pressure Systems International ATIS Tire Inflation System, PRO-LB emphasizes automatic load-responsive pressure adjustment rather than maintaining only one fixed inflation target.

Best Fit For

Trailers with widely changing payloads
Fleets accumulating substantial empty or lightly loaded mileage
Applications experiencing irregular wear from excessive pressure at low load
Selected Hendrickson INTRAAX-equipped trailers
Selected Hendrickson VANTRAAX-equipped trailers
Selected Hendrickson ULTRAA-K-equipped trailers
Dual-tire trailer applications
Wide-base single-tire trailer applications
Fleets seeking automatic inflation and pressure relief
Operators focused on tire life, uptime, and fuel efficiency

Related Vehicle and Trailer Types

Related Truck and Trailer Models

Related Tire and Wheel Types

Related Tire and Wheel Products

Related Equipment Systems

Related Guides

Regulatory and Compliance Notes

TIREMAAX PRO-LB does not change the tire, wheel, axle, suspension, or trailer load ratings. Inflation settings must remain within the approved limits of every component and satisfy the tire manufacturer’s requirements for the actual axle load.

Commercial tires must still meet applicable inspection, tread-depth, condition, load, and inflation requirements. An automatic inflation system does not make a damaged, overloaded, or improperly matched tire compliant.

Installation and repair work must preserve brake operation, air-system integrity, wheel-end sealing, electrical function, and required trailer safety systems.

Real World Operating Notes

PRO-LB is particularly relevant for fleets whose trailers frequently alternate between loaded and empty operation. Maintaining maximum-load pressure during every empty mile can reduce the tire contact patch and contribute to irregular wear.

Audible air exhaust from the controller can be normal when the system is reducing pressure. Trailers should carry the applicable warning label so drivers and technicians do not automatically treat every relief event as a leak.

Cold tires may lose pressure while parked. The indicator lamp may illuminate at startup while the system restores the correct load-based value.

The system improves pressure management but does not eliminate manual inspections. A tire can retain pressure while still having tread separation, impact damage, exposed reinforcement, or other unsafe conditions.

Frequently Asked Questions

What is Hendrickson TIREMAAX PRO-LB?

It is an automatic trailer tire-pressure control system that inflates, relieves, equalizes, and adjusts pressure according to axle load.

How does PRO-LB determine trailer load?

It monitors suspension air-spring pressure. Higher air-spring pressure generally indicates greater axle load, allowing the controller to increase the tire-pressure target.

Can the system remove air from the tires?

Yes. PRO-LB can relieve excess pressure caused by changing load, temperature, or operating conditions.

What pressure range does PRO-LB support?

Hendrickson lists 85 to 120 psi for dual-tire settings and 100 to 120 psi for wide-base single-tire settings.

Will PRO-LB completely deflate tires when the trailer is empty?

No. The controller maintains a minimum threshold. Hendrickson lists 75 psi for dual tires and 90 psi for wide-base single tires.

Why is air exhausting from the controller?

The system may be relieving pressure as part of normal operation. Continuous or unexplained venting should still be inspected for incorrect adjustment, an excessive load signal, contamination, or controller problems.

What does the indicator lamp mean?

It normally indicates that the system is actively supplying air or requires attention. A lamp that remains on for more than approximately ten minutes can indicate a low tire, air leak, insufficient supply, or system problem.

Can PRO-LB be installed on any trailer?

No. It requires a compatible air suspension, axle, wheel-end configuration, tire arrangement, air supply, and approved Hendrickson application.

Does PRO-LB replace manual tire inspections?

No. Drivers and technicians must continue inspecting tire pressure, tread, sidewalls, valves, wheels, hoses, and wheel ends.

How are replacement parts identified?

Use the trailer VIN, suspension model, suspension category, controller part number, pressure settings, axle information, tire arrangement, and individual component numbers.

Availability and Where to Find

Hendrickson TIREMAAX PRO-LB may be available as original equipment on compatible trailers or as an approved retrofit for selected Hendrickson suspension, axle, and wheel-end configurations.

Systems and replacement parts may be available through Hendrickson distributors, trailer manufacturers, commercial-trailer dealers, heavy-duty parts suppliers, tire-inflation specialists, and qualified trailer repair facilities.

Current product information, application details, service literature, parts information, and support resources are available through the Hendrickson TIREMAAX PRO-LB website.

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