Why TPMS?

Congress passed the Transportation Recall Enhancement, Accountability and Documentations Act, also called the TREAD Act, in 2000 in response to a major recall of defective tires that created unsafe driving conditions.

The TREAD Act mandates that new vehicles less than 10,000 pounds gross vehicle weight sold in the United States be equipped with tire pressure monitoring systems, or TPMS, beginning with the 2006 model year. TPMS systems alert drivers when the pressure in a tire falls more than 25 percent below the manufacturer's recommended tire pressure. The TREAD Act affects passenger cars, light trucks and buses. Light-duty vehicles with dual-rear axles are excluded.

Indirect TPMS systems use the vehicle's ABS system to calculate the difference in tire diameters and approximate tire pressure.

Direct TPMS systems include small sensors that are installed inside the tires. These sensors monitor tire pressure and continually relay this information, via radio signals, to the vehicle's electronic control unit (ECU). If tire pressure falls below required limits, a warning light on the instrument panel alerts the driver about the problem.

The TREAD Act requires vehicle manufacturers to equip 20 percent of their 2006 model year vehicles with TPMS. The number increases to 70 percent of 2007 model vehicles, and to 100 percent of all 2008 model vehicles.

System performance requirements

The TREAD Act outlines a number of specific TPMS performance requirements:

• New vehicles must be equipped with sensors that monitor tire pressure in all four tires. Monitoring the spare is not required.
• The TPMS system must operate when the vehicle ignition is on and warn when tires are under-inflated by 25 percent or more.
• The TPMS system must alert the driver when there is a system malfunction.
• The TPMS warning light must stay on until the tire is inflated to the proper pressure or the system malfunction is corrected.
• A bulb check of the warning light on the instrument panel must occur whenever the ignition is turned on.
• Vehicle owner's manuals must contain warnings about potential incompatible replacement tires for the vehicle.

Safety and performance

Monitoring and maintaining proper tire pressure increases driver safety and improves vehicle performance in a number of important ways. Properly inflated tires:

• Improve vehicle handling
• Reduce braking distances
• Lower the risk of hydroplaning
• Decrease tire wear
• Improve fuel efficiency

TPMS can save lives

Most people ignore their tires, yet tires are undoubtedly one of the most critical safety components on a vehicle. Where the rubber meets the road affects traction, handling, steering, stability and braking. Because of this, a sudden tire failure can have serious consequences, especially if it occurs when operating at highway speeds.

• Nearly 250,000 accidents occur in the United States per year due to low tire pressure.
• About 75 percent of roadside flats are preceded by a slow leak or under inflation.
• According to a recent survey, America could reduce its fuel consumption by 10 percent and save a collective $2 billion a year by keeping tires properly inflated.
• A tire can lose up to half of its air pressure without appearing to be under inflated.
• NHTSA estimates that tire pressure monitoring systems could prevent as many as 79 deaths and 10,365 injuries each year in the United States.