How to check your tyre pressures correctly

By Daniel Gardner, 24 Nov 2017 Car Advice

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How to check your tyre pressures correctly

Don’t let the variety of different tyre inflators discourage you from checking one of the most important maintenance items

It should be no secret just how important correct tyre pressures are. Not only will a vehicle rolling on well-maintained tyres turn, stop and accelerate safely and more comfortably, it will also return the optimum fuel economy, so it should be top of the list of weekly jobs you can take care of yourself.

Some motorists may find the range of inflators found on service station forecourts confusing, but checking and correcting your own tyre pressures is a simple job.

The most simple and increasingly common solutions are the fully automatic systems that only require you to pre-set the pressure and connect the hose.

Read the correct pressure from your tyre placard, which can be found inside the door jamb, behind the fuel filler cap or in the owner’s manual. There is often a table with a few possibilities, which allows you to select the correct pressure even if you are carrying a full load of passengers with luggage, and for each tyre size fitted as standard. Check the sidewall of the tyre and match it to the information on the placard to find the pressure you need.

The pressure will be stated either in bar or PSI which you will need to select on the inflator with the simple press of a button. With a few more prods of the up or down buttons you can set the required figure.

Then remove the dust caps and attach the air hose by squeezing the tab and releasing once the fitting is pressed onto the tyre valve. You won’t need to hold the hose in place as long as the locking tab is working correctly.

You don’t need to watch the display but it is a good idea to observe the pressure before correction to see if your tyres are holding air with a good seal. If one particular tyre is dropping more pressure than the others it may indicate it has a slow leak or puncture.

When the machine beeps, it has set the pressure. Replace the dust caps to finger tight and you are good to go. Some early tyre pressure monitoring systems require a reset before moving off.

If the service station has a more traditional inflator with gauge the process is only a little more complicated.

Simply attach the hose in the same way you would the fully automatic version and watch the sliding bar or rotating needle gauge. The inflator can add air to the tyre by squeezing the trigger all the way but can also allow air back out again by partly depressing it, if you have accidentally over inflated. Others have a small separate button for releasing excess pressure.

Remember that a manual inflator will only give you an accurate reading after adding air so if you have to remove a little pressure, be sure to give the trigger a quick full press before reading again.

An accurate reading is also only possible if the inflator is in good condition. If you suspect the equipment is not up to scratch it’s a good idea to have your own pressure gauge that can be stored in the glove box out of harm’s way and can be used to give one final check once you think you are done.

Always try to check the pressures when the tyre is cold as a long journey or hard driving will increase the temperature and the pressure will rise. The same will happen in hot weather or if the tyre has been in direct sunlight.

When you are up close and personal with your tyres, you can also use it as an opportunity to check the general condition. Any perishing rubber, splits, bulges or other damage should be inspected by a good mechanic or tyre shop. If the tread is worn out, it’s time to replace them.