The TREAD (Transportation Recall Enhancement, Accountability and Documentation) Act requires that 100% of all passenger cars, light trucks, and buses manufactured in the United States after September 2007 be equipped with a tire pressure monitoring system.
Vehicles must be equipped with:
- A tire pressure monitor in all four tires
- A system that operates when the vehicle is on and warns the driver when tires are under-inflated by 25% or more.
- A system that alerts the driver of a tire pressure monitoring system malfunction
- A TPMS warning light that stays on until tire pressure has been inflated to vehicle specifications
- A "bulb check" of the TPMS warning light on the instrument panel that blinks when the ignition is turned on
- Vehicle owner's manuals that contain warnings about incompatible replacement tires for the vehicle
