What PSI should my car tyres be?

August 3, 2022

With so much on our minds, it’s easy to forget about regular tyre pressure checks. But it’s in your interests not to ignore car tyre pressure checks.

Keeping tyres at their optimal tyre pressure means your vehicle handles well and operates more efficiently. Maintaining correct tyre pressure reduces the likelihood of emergency breakdowns or accidents on the road, and you also save money (correctly inflated tyres help tyres last longer).

Signs your car tyre pressure is off:

  • You’re getting lower gas mileage than usual
  • Your steering seems sluggish
  • Your car seems to sit lower to the ground than normal

You can have your tyre pressure checked at a tyre shop, or do it yourself.

Let’s look at all things car tyre air pressure, including understanding what PSI is, why you should maintain correct air pressure for car tyres, and how you can do your own tyre pressure checks. 

Why does car tyre air pressure matter?

Your tyres will last longer if kept at their recommended tyre pressure. If your car tyre pressure’s not correctly maintained, tyres may not perform correctly, and/or may wear in ways they aren’t designed to.

Implications of low tyre pressure

For standard driving on bitumen, under-inflated tyres can stress the sidewalls of the tyre. You may see cracks or bulges in the tyre as a result. Premature wear on tyres can be hazardous, which is why tyre pressure checks are vital.

Implications of over-inflated tyres

Over-inflated tyres won’t grip the road as they should. They may wear out in the centre of the tyre, as only the smaller rounded surface in the centre of the tyre is connecting with the road, rather than the full surface area of the tyre.

In addition to wear, over-inflated tyres may result in a:

  • Bumpy ride
  • A car that doesn’t handle well
  • Higher likelihood of blowouts or punctures.

What’s the ideal tyre pressure?

Finding out the appropriate air pressure for your car tyres is relatively easy. 

You can see the ideal tyre pressure for your particular tyres by looking at the vehicle tyre placard this can be found  on the inside of your driver-side door, Fuel filler cap, Glovebox or Under the Bonnet. If you can’t find a sticker there, check your vehicle owner’s manual for the recommended tyre pressure for your vehicle.

In general, a passenger vehicle will have a recommended PSI of 32 to 35, but always go by the recommended tyre pressure for your actual vehicle.

Note, some tyres feature a pressure. This refers to the maximum pressure the tyre can be inflated to—not the recommended pressure for your particular vehicle, so do not inflate to this amount.

What is PSI?

PSI stands for pound-force per square inch, and refers to the amount of force exerted on a surface, per unit area. Though PSI is an Imperial measurement, it is still the most commonly used measurement for car tyre air pressure in Australia.

You may find other types of measurements specified in your car’s user manual, such as BAR and kPa. BAR is a metric unit used for measuring atmospheric pressure, (1 Bar is equal to 14.50 pounds per square inch).  kPa, or kilopascal, is a metric unit equal to 1000 pascals.

Most service station tyre pressure gauges are set on PSI, but include the option to change the unit of measurement. If the pressure gauge/pump doesn’t convert, you can convert using an online conversion calculator. There’s also a handy conversion table here.

When is the best time to check tyre pressure?

It’s not a wise idea to wait for your car’s regular service for your tyre pressure to be checked. 

While tyre pressure will usually be checked as part of a standard service, monitoring of your tyre pressure should occur more often. Here are some suggestions for when to check your car tyre pressure.

  • Check your tyre air pressure every 2nd to 3rd time you get petrol.
  • Check your car tyre pressure when the tyres are cold. Why? The air pressure in tyres increases when friction with the road heats them up. So check your tyres using a tyre pressure gauge first thing in the morning before you drive, or after your car has been parked for a few hours.
  • Check (and adjust) your tyre pressure according to your driving speed and road conditions.

For instance, if you drive your vehicle at sustained high speeds or carry heavy loads, you may need to increase the cold inflation pressure of your tyres to compensate for extra strain. On the other hand, if you’re planning to drive off-road and on dirt, sand or mud, you may need to lower tyre pressure to retain traction and prevent puncture.

In short, the surface you’re driving on, and the speed you are going, dictate optimal tyre pressure. Check your tyre and vehicle specifications for optimal tyre pressure for driving in different conditions. Here is more useful information on tyre pressure for off-road driving.

*Note, car tyre pressure changes whether you drive your vehicle regularly or not. So, even if your car has been garaged for a long period of time, you still need to get the tyre pressure checked.

What’s the best way to ensure my tyres are the right pressure?

Unless you have a tyre pressure gauge at home, the easiest way to check your pressure is to use the tyre pressure gauge at your local service station.

Tyre Placard sticker, you then need to:

  1. Set your required pressure on the pressure gauge
  2. Take the air hose to your tyre.
  3. Unscrew the cap from the tyre valve.
  4. Attach the hose to the tyre valve (there’ll be a little snap as it locks into place). You’ll hear hissing if it’s not attached properly, so try again if it doesn’t work on the first try.
  5. Leave the air hose attached until you hear a beep, which means your tyre has reached the programmed pressure.
  6. Remove the air hose and replace the tyre valve stem cap.
  7. Repeat for all 4 tyres, remembering that recommended PSI will usually differ between front tyres and rear tyres.
  8. Return the air hose to the tyre pressure gauge.

Car tyre pressure checks 

Even easier is to have a mobile tyre expert visit you! It’s quick, can be done at your home or workplace, and alleviates any concerns you may have about doing it yourself.

Jim’s Mobile Tyres offer super quick tyre pressure checks as a standalone service, or as part of our other tyre services like tyre fitting, tyre rotations, and tyre puncture repair.

We will inflate your tyres to the pressure specified by the Vehicle Tyre Placard, and of course explain any issues of note that arise from the tyre servicing.

Contact us for a tyre pressure check today.

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