Two types of TPMS - Direct TPS & Indirect TPMS
Indirect TPMS systems employ wheel speed sensors on a vehicle’s anti-lock brake (ABS) system to track each tyre’s rotation. The premise is that under-inflated tyres have a smaller radius, resulting in a higher rotational speed compared with a fully inflated tyre. The sensor detects the faster rotation, and the system alerts the driver. The change in radius is small, making indirect measurement less consistent than direct pressure measurement.
Technical features of TPMS
How to keep your tyres properly inflated:
1: Check tyre pressure at least once a month and before going on long trips. Since temperature affects tyre pressure, it is best to check tires when they are cold, i.e. haven’t been driven on for at least three hours.
2: Fill your tyres with the pressure recommended on the tyre label, normally located on the drivers door frame, sill or edge or on the inside of the fuel filler cover.
3: If you have any questions about your tyres or maintenance, check your owners manual or consult your dealer.
FAQ - Questions and answers:
Q: WHY IS PROPER TYRE INFLATION IMPORTANT:
A: Keeping your tyres at the recommended pressure is essential for the safe and efficient operation of your vehicle. Safety experts estimate that 25 percent of vehicles are running on tyres with lower than recommended pressure. Properly inflated tyres run cooler, last longer, and improve fuel economy.
Q: WHY DOES TYRE PRESSURE CHANGE:
A: Many factors affect tyre pressure, and that is why it is so important to check your tyres at least once a month and before going on long trips. Tyre pressure can decrease due to tyre damage, slow leaks, or changes in outside temperature. For example, when the weather changes, your tyre pressure changes too. For every drop of 5 degrees Centigrade in temperature, your tyres lose 1 psi. Tyres also deflate naturally over time, as much as 1.5 psi per month.
Q: HOW DOES THE NEW TYRE PRESSURE MONITORING SYSTEM WORK?:
A: Sophisticated sensors in the vehicle continuously monitor tyre pressure, and the warning light goes on when a tyre is 25 percent or more below the appropriate tyre pressure.
Q: WHEN WILL THE NEW TYRE PRESSURE MONITORING SYSTEM BE AVAILABLE? :
A: The EU requires all new vehicle models from 2012 to be equipped with TPMS. In the U.S. Tyre Pressure Monitoring Systems have been mandatory on all passenger cars and light trucks from the 2008 vehicle model year. Check your owners manual to see if your vehicle is equipped with a Tyre Pressure Monitoring System. Many models have already been equipped with a system.
Q: IF THE WARNING LIGHT GOES ON AND OFF, WHAT DOES THAT MEAN? :
A: On cold mornings, the warning light may illuminate and then extinguish as tyre pressure increases due to driving or outside air temperature increases. Additionally, if the warning light goes on and off, a malfunction in the system is indicated by a blinking light (for a period of 60 seconds to 90 seconds). After blinking for the brief time, the warning light can remain on. You should then contact your dealer for a system inspection.
Q: HOW SOON DO I NEED TO FILL MY TYRES IF THE LIGHT GOES ON? :
A: Please heed the warning light and check your tyres as soon as possible.
Q: DOES THE WARNING LIGHT ALWAYS MEAN THAT THE TIRE PRESSURE IS LOW? :
A: The warning light may indicate a system malfunction requiring a dealer's attention. If the warning light flashes before it is continuously on, but the tyre pressure is found to be within the appropriate range, contact your dealer for a system inspection.
Q: WHAT ELSE DO I NEED TO DO FOR TYRE SAFETY? :
A: The Tyre Pressure Monitoring System is a tool to keep you informed about low tyre pressure, but it is no substitute for regular tyre maintenance. Check your tyre pressure and look for cuts and other damage to each tyre at least once a month and before going on long trips. Consult your owners manual on replacing a tyre or using a spare tyre