How do tire pressure sensors work & are they reliable?

Here's why your vehicle's built-in tire pressure monitoring system should be used as a last resort

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Chances are, if your car is anything approaching modern, it has a tire-pressure warning system. Get a low tire, a light turns on in your instrument panel.

They work by using a sensor inside the tire, mounted on the wheel, that tracks pressure and sends a signal by radio to the car’s control unit. Because tire pressures normally fluctuate during driving, particularly as the tires heat up, these aren’t the most sensitive sensors you can find.

After all, you don’t want the sensors going off for just nothing, right?

Tire pressure sensors are a last resort!

What that means is you have to treat the tire pressure monitoring system as a last-resort warning rather than assuming the lack of a warning means all is well. Some systems don’t go off until the pressure is as much as 25 per cent down.

That’s dangerously low, so the trick is to keep checking your tires even when your new car has a fancy tire-pressure system.

But when that low pressure indicator does light up, don’t freak out. According to Consumer Reports here, the culprit could be a number of things include falling temperatures.

How to reset the tire pressure sensor

Resetting the system, once you’ve found the low tire and inflated it properly, varies from vehicle to vehicle, so check your owner’s manual. If you see a button with an illustration of a cross-section of tire, that’s more than likely it. Push and hold.

Why low tire pressure matters in the first place

Tires with less than desirable pressure creates uneven wear, leading to sidewall-killing heat that turns your vehicle’s handling to mush – and that’s obviously not good, especially for more expensive rubber such as high-performance tires.

But too much pressure is equally harmful, also creating uneven wear and leading to inadequate handling, or worse, a tire blowout.

Low pressure allows the sidewalls to flex too much, generating heat, and it also increases the odds of wheel damage when you hit a pothole. The softer sidewalls are more likely to crush on impact to the point your wheel takes a hit.

It also turns the rolling surface concave, putting more wear on the treads on the sides than on the centre. Because the tires are flexing so much, your handling suffers, too.

Too much pressure turns the rolling surface convex, putting more wear on the centre treads than the sides, and because it’s riding on the centre instead of the entire tread, you don’t get the turning power or traction you should.

Kelly Taylor
Kelly Taylor has been writing about cars since 2000. His favourite ride has been the Audi R8 from Thunder Bay to Winnipeg, where he nearly traded the car for a Ford Ranger, a Greyhound Bus and the Blue Heron Gift Store in Kenora, Ont.