How to check your tyre pressure
Yes, you do have to get your hands a little dirty to look after your tyres. No, it’s not difficult, writes David Linklater.
One of the basics of car maintenance is keeping tyres at the correct pressure. It’s also one of the most overlooked, even though that rubber is the car’s only point of contact with the road.
Tyres are not a set-and-forget item. Even if you start out with all four corners pumped and primed to manufacturer-specification, there’s some natural loss of pressure over time.
If your tyres are set at 32 pounds/square inch (psi) and you lose 1psi per month (entirely possible), after a year you’ll be seriously underinflated.
Nor can you simply ‘‘keep an eye’’ on them. A tyre may be up to 50 per cent deflated before the sidewall obviously starts to sag.
Incorrect pressures (low or high) can cause excess tyre wear, increase fuel consumption and even adversely affect handling/ braking (and therefore safety) in extreme circumstances.
Keeping tyre pressures up to spec is actually not that difficult. You can check them at home (indeed, you should check them at home for reasons we’ll get to in a minute) and should do so at least once a month. Why not make the first day of every month Tyre Day? Then you won’t forget.
The first thing you need to know is what the correct pressures for your car are. This information is most accessible on a physical plaque: either inside the driver’s door frame, or sometimes on the fuel flap.
You can also look in your car’s handbook, which might be made of paper (old-school) or if you have a late-model vehicle, might even be available digitally via the infotainment system or on a mobile-phone app.
The pressures might be expressed in different or unfamiliar ways, but the Google machine can easily convert them to your preferred format. Pounds per square inch (psi) is common, as are kilopascal (kPa) and bar (which is actually 100 kPa). They’re all units of measure for pressure.
You need to check the pressure of each tyre individually of course – and also double-check that your vehicle doesn’t require different pressures front-to-rear (some do).
Ideally you’ll have a portable/ personal gauge, which you can buy from any automotive parts store (as little as $10, although you might want to spend a little more). Such a device is likely to be more accurate than a well-worn servicestation gauge, although the latter is also fine – as long as your local servo isn’t too far away.
That’s because you should check pressures when the tyres are cold to get an accurate reading; preferably when the car has been parked for over two hours. If you must travel to a service station, do so at moderate speed, ideally to a location no more than 2km away.
Taking a reading is easy: simply unscrew the valve cap (which keeps dirt out rather than keeping air in) and press the gauge firmly, straight onto the valve-stem. There’ll be a hiss and you should get a reading instantly – in what format will depend on the device, in which case refer to that Google conversion.
For example: the Skoda Octavia in our pictures runs 2.3 bar in all four tyres (as stated on the plaque), which converts to 33psi (the format of the gauge we used).
If your tyres are low, you can either top them up with a compressor at home (no, we don’t have one of those either) or use the pump at your local service station. There are different kinds, but they’re generally pretty easy to use: many allow you to set the desired pressure on the machine and will automatically inflate (or even deflate if needed) the tyre to that level when you press the hose onto the valve stem.
It doesn’t have to be an absolutely exact science. Feel free to adjust pressures in line with your usage. If you’re carrying a heavy load in back, for example, you can bump the pressures up by a few psi at the rear – as long as you keep it consistent across both sides and remember to take them down again when the hard work is done. By the way, if there’s a ‘‘max pressure’’ given for your car, that’s the level of inflation at which the car can carry its maximum rated payload. It doesn’t mean that the tyre will go ‘‘pop’’ if you go 1psi beyond.
Some cars have automatic tyre pressure monitoring systems, but they too require maintenance. The most common type simply monitors wheel rotation using the anti-lock braking sensors, and will warn you if one or more wheels are spinning faster than the others for a sustained period. Handy, but this system only works if it’s reset when all four tyres are correctly inflated.
Some monitoring systems actually have tiny pressure gauges inside each wheel, so they can alert you to any loss straight away – but also tell you how much has been lost.
Again, worthwhile tech but not infallible; don’t let it stop you doing a proper manual check as you normally would.
Here’s another question you might not have considered: what should you fill your tyres with?
Air or... something else? Many tyre suppliers will now fill your tyres with nitrogen, as used for racing cars, aircraft and other vehicles that have to function precisely in extreme conditions.
It’s not as exotic as it sounds, because air is 78 per cent nitrogen anyway. But pure nitrogen is more stable, there’s less seepage (so pressures will be maintained for longer) and much less moisture to corrode your rims in the longer term.
Charges vary but our local tyre shop quoted all four tyres for $40, or $65 with a basic service check thrown in.
The tangible/cost benefits are open to debate (and people do debate them). But nitrogen is unlikely to improve your family car’s performance and safety beyond keeping tyre pressures stronger for longer if they are neglected. The most important thing is keeping the tyre pressures correct, regardless of what’s inside them.
The downside with nitrogen, of course, is that you need to be topped up with the same stuff when the time comes. You can use normal compressed air if you’re stuck, but then that rather defeats the purpose of paying for the nitrogen in the first place.