Tire Pressure Basics & Maintaining Inflated Tires

Tire Pressure basics tractionlife

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Pressure is a good thing. Our expert advice including the dangers of low pressure, how modern tire pressure sensors work and whether they’re reliable, how to check tire air, the 3 common types of gauges, and finally how to inflate tires and keep them pumped for those long drives. 

by Kelly Taylor

Quick, what does your vehicle ride on?

If you said tires, you’re not quite there. Your vehicle rides on air. The tires are there primarily to hold the air in.

When you look at tires that way, it makes it easier to understand why it’s so important to ensure your tires are at their optimal inflation pressures.

Low Tire Pressure: The Dangers

Low pressure creates uneven wear, it generates sidewall-killing heat and turns your vehicle’s handling to mush.

Excess pressure creates uneven wear, it increases the chance of a blowout and turns your vehicle’s handling to mush.

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.

Tire Pressure Sensors: Are They Reliable?

tire pressure sensor indicator

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.

How do tire pressure sensors work?

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?

so the trick is to keep checking your tires even when your new car has a fancy tire-pressure system.

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.

How To Check Tire Pressure

When your vehicle has just been driven, the air inside your tires will be warm. Warm air expands, so check your tires now and you’ll get a false reading. It’s best to check your tires when your car has been at rest for at least an hour. 

Using either an electronic tire gauge or old-fashioned stick type, place the end of the gauge on the tire nozzle (remove the cap first, of course) and seat the rubber on the gauge on the nozzle and then press and hold until you get a reading. If you hear air escaping around the nozzle, pull the gauge off and start over.

Warm air expands, so check your tires now and you’ll get a false reading. It’s best to check your tires when your car has been at rest for at least an hour. 

So, what should my tire pressure be?

Your tires are at the correct pressure when the gauge shows the same numbers as on the tire pressure sticker on your driver’s door jamb or in the manual. Ignore any numbers you see on the tire itself, as those represent maximum pressures.

Usually, the front tires will have slightly different recommended pressures than the rear tires. That’s OK. Some engineer who has forgotten more about tire pressures and suspension systems than most people know has arrived at that number after some careful calculations. Go with those stated numbers and ignore anything else you might hear. 

Tires will gradually lose pressure even when in top condition. It’s usually a loss of air through the sidewalls. If your tire loses pressure rapidly, there’s usually an issue, either a puncture or an issue with the valve stem. 

Tire Pressure Gauges

There are three types of gauges you can buy. The cheapest, and good enough for most applications, is the stick type that resembles a ballpoint pen. These run around $10.

Digital tire gauges: do they work better?

A digital gauge will be more accurate, and is only $6 to $10 more. The other advantage is these typically have backlit LCD screens, making them good choices if you’re checking pressure in low-light situations, such as your garage.

A dial type has a face that resembles a watch, which can make it a bit easier to read than a stick, but these aren’t necessarily any more accurate and can be susceptible to permanent loss of accuracy when dropped. These sometimes come with a hose for attaching to the wheel, which means they require two hands to operate and are more awkward.

3 types of tire gauges:

3 types of tire gauges tractionlife

In all cases, protect your gauge from impact, such as dropping it, and keep it at room temperature rather than leaving it in your glovebox. Electronics work better at room temperature and any lubrication on mechanical gauges will be at a better viscosity, too.

Whichever type you buy, consider that you’ll need to check the pressure in a compact spare, if your vehicle is so equipped. These are typically inflated to 60 psi, so make sure your gauge goes to at least 70.

Keeping the Air in Those Tires

Air compressor is the way to go

Since bicycle tires are usually inflated more than car tires, even a bike pump can be used for your vehicle’s tires. Most people will want to use an air compressor, however. Gas stations that offer service sometimes leave a hose out near one of the service bay doors but more common are units that require payment to operate.

Where to inflate them

If you long for the days when air was free, remember that the air hose left out for you was simply supplying surplus air from the compressor used to drive the station’s power tools. If a station doesn’t have service bays, then it will have had to purchase and install a compressor for customer use alone, so don’t necessarily begrudge the need to pay. Some stations offer free air for even a small purchase, as well.

Summer tire inflation

In summer, inflating tires is as simple as putting the end of the hose on the valve and holding it on until the tire is inflated. If it sounds as though most of the air is going into the tire, you’re doing good. If you hear a lot of air escaping, simply reposition the hose on the valve until it stops. Pull the hose off and recheck the pressure and keep inflating and checking until the tire is at the specified pressure. Most tire gauges also have a little nib you can use to press in on the valve stem to deflate the tire if you go above the specified pressure.

Winter tire inflation

In winter, consider the compressed air might have a bit of moisture, or there could be moisture on the valve stem. Either way, it’s possible this moisture might freeze in the valve stem and hold it open, causing a slow leak. A little spritz of water-displacement fluid (such as WD40) on the valve prior to and after filling can help avoid this.

Make sure you replace the valve stem caps, as these keep dirt and moisture out of the valve.

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