Tyre Myths: Do Tyre Pressure Monitoring Systems Tell You When You Need to Change Your Tyres?
Modern Sensors Make Driving a Breeze
Modern cars make driving a lot easier with all the things they do for us. You no longer need to turn your headlights on when it’s dark, or your windscreen wipers when it rains. You are warned when you drive over the speed limit. They may even tell you what your tyre pressure is. But do modern sensors know how to warn you when your tyres need changing?
What are Tyre Pressure Monitoring Systems (TPMSs)?
A Tyre Pressure Monitoring System does exactly what it says on the tin. It is an electronic system installed on your car to monitor the air pressure in your tyres.
Modern cars (typically from 2008 onwards) often come with a TPMS installed. The systems use sensors to continuously monitor the pressure of the air in your tyres. A warning light on your dashboard signals when your tyre pressure becomes dangerously low. This warning is a safety feature to prevent you from driving on dangerous tyres. The TPMS can also help you improve the longevity of your tyres by maintaining the correct PSI.
How Do TPMSs work?
Not all TPMSs are the same. The low tyre pressure warning light on your dashboard is the last step for an indirect TPMS or a direct TPMS.
· Indirect TPMS
An indirect TPMS uses wheel speed to calculate pressure. Rather than measure the pressure in the tyre, the system uses wheel speed sensors from the antilock brakes. Based on the speed of each tyre, an onboard calculator works out the amount of revolutions a tyre is doing. The number is interpreted to figure out the pressure of the tyres, with underinflated tyres spinning faster than they would at correct inflation.
· Direct TPMS
A direct TPMS uses pressure sensors in the wheel to calculate the PSI. A direct TPMS is more reliable than indirect, as you get a specific tyre pressure reading rather than an interpretation. Measurements from the direct TPMS are analysed by an onboard computer, and, if the pressure is lower than recommended, a warning light will flash on your dashboard.
Data from sensors is sent wirelessly to the onboard computer. To ensure that your tyre pressure is not from another vehicle, each system has its own unique serial number.
When Do You Need to Change Your Tyres?
A TPMS is great for warning you when you need to inflate your tyres. However, there are no sensors to warn you about tread wear or other hazards that mean you need to change your tyres. Instead, you should include a tyre inspection as part of your regular tyre maintenance routine. Here are some examples of signs that you need to change your tyres:
- Tread depth gets too low: The legal minimum tread depth in Australia is 1.5mm. Tread depth has an impact on stopping distance, and some vehicle manufacturers argue that minimum tread depth should be legally increased to 2mm or 3mm.
- Uneven tyre wear: Uneven wear is an indication of unusual stress on a tyre. Causes include incorrect wheel alignments or the wrong air pressure in your tyres.
- Tyre age: You may use your vehicle infrequently and not put a lot of wear on your tyres. However, vehicle and tyre manufacturers still recommend you change your tyres regularly. Tyres over five years old dry out, losing elasticity and becoming increasingly dangerous to use.
What Do the Experts Have to Say?
Vehicle and tyre manufacturers have often worked together in creating TPMSs. They will both agree that they are helpful tools and useful for maintaining safe air pressure in your tyres. However, they also agree that while the systems are useful, they cannot warn you when you need fresh tyres.
For example, Bridgestone says:
“Tyre Pressure Monitoring Systems are only able to keep track of the amount of pressure within a tyre. They do not indicate whether a tyre has worn out its tread or the right time to replace it.”
If your TPMS continually signals a warning, you should get your tyre checked by a professional. Feel free to contact us to book an appointment or ask any questions you may have.
Keeping your family and fleet safe on the road,