Are my tires properly inflated?

2014/08/04

Have a look at the two driver’s side tires on your car sometime. If one was 30% underinflated, do you think you could tell which one just by looking at it? Surprisingly, mostly people can’t, and this fact alone should have drivers running for their tire gauges on a regular basis!

Know your tires

Most people only think about their tires when it comes time to change them or if they have a flat. But the fact is your tires serve some not-so-obvious functions. Properly inflated tires contribute to better adhesion to the road in wet conditions, optimize fuel economy, and help shorten braking distances. Underinflated tires, even just 30% underinflated (that’s right, the amount you thought you could easily detect by eye, but it turned out you couldn’t!), can lead to premature tread wear, internal friction causing heat in the sidewall, and ultimately tire failure. In fact, 75% of roadside flats are caused by a slow-leak or the consequences of underinflation. Lastly, properly inflated tires give your vehicle exactly the right road feel the vehicle designers intended.

The cold hard facts on tire pressure

In most parts of Canada, where the summer to winter temperature difference is easily 50 to 60 degrees Celsius, we had all better keep in mind that tire pressure drops 1 psi for every 5.5°C drop in outside temperature. So a tire that starts out at 30 psi at 30 degrees would, left on its own, drop to around 20 lbs pressure on a very cold winter’s day. (There’s that 30% drop you can’t detect visually again.)

We know that the temperature doesn’t change that drastically overnight, but tire pressure is something you need to keep an eye on every few weeks, and obviously from season to season.

So if you can’t depend on your eyes and your TPMS (Tire Pressure Monitoring System) only alerts you at 25% loss in pressure, what can you do? The answer is to buy yourself a decent tire gauge and make a habit of checking your pressure throughout the year. And don’t trust the read out on a coin operated air compressor, there’s no guarantee it’s reading correctly.

Lastly, always check the pressure on a cold tire, like in the morning before you use your car.

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