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Why tyre pressures matter more than most drivers think

Your tyres are the only part of the car actually touching the road, and the pressure inside them shapes how they perform. Get it right and you will notice sharper steering, shorter braking distances in the wet and a slightly healthier fuel bill at the pumps. Get it wrong and you will be spending money at the tyre fitter far more often than you would like.

Under-inflated tyres squirm about, run hot and scrub their shoulders away. Over-inflated ones make the centre of the tread bulge outwards, so the middle wears faster than the edges. Both extremes hurt grip, and both cost you money. The good news is that checking pressures takes about five minutes and needs nothing more than a decent gauge and a bit of routine.

Finding the correct pressure for your car

Ignore whatever number is moulded into the tyre sidewall — that is the maximum the tyre can safely hold, not the pressure your car needs. The correct figure lives on a sticker inside the driver's door shut, on the fuel filler flap or in the handbook. Most family hatchbacks sit somewhere between 30 and 36 psi, but the number varies by model, engine size and wheel size, so always go by the sticker.

Many cars quote two sets of figures: a normal load and a fully laden one. If you are packing four adults and a boot full of luggage for a holiday, use the higher figure. If it is just you commuting, the lighter setting gives a more comfortable ride. Some stickers also list a higher rear pressure for towing, which is worth checking before you hitch up a caravan or trailer.

A few practical points worth remembering:

• Check pressures when the tyres are cold — before you have driven more than a mile or two, or at least three hours after a run. Warm tyres read higher and will mislead you.
• Check monthly and before any long journey, plus once the weather turns properly cold.
• Pressures fall roughly 1 psi for every 10°C drop in ambient temperature, so a tyre that was fine in September can be noticeably soft by January.
• Don't forget the spare, if you have one. A space saver usually needs a much higher pressure — often around 60 psi.

What uneven wear is telling you

Tread wear patterns are a bit like a diagnostic readout. Read them carefully and they will often point you towards a problem before it becomes expensive. Here is what to look for.

Wear on both outer shoulders almost always means the tyre has been running under-inflated for a while. It may also suggest hard cornering, but pressure is the first thing to check.

Wear down the centre of the tread points to over-inflation. It is common on cars that rarely carry a load but are pumped up to the fully laden figure "just in case".

Wear on one shoulder only is a strong hint that the wheel alignment is out. Kerbing, potholes and worn suspension components all knock camber and toe out of spec, and the tyre pays the price.

Feathering or a sawtooth pattern across the tread usually means excessive toe-in or toe-out. You may also notice the car wandering or the steering feeling vague.

Bald patches or flat spots can indicate worn shock absorbers, seized brake calipers or a wheel that has been locking under heavy braking.

Cracks, bulges or embedded objects in the sidewall are not wear patterns as such, but they are a reason to replace the tyre immediately. A bulge means internal cord damage and a potential blowout.

The alignment and suspension connection

If a new set of tyres starts wearing oddly within a few thousand miles, the tyres are not the culprit — something in the suspension or steering is. Worn track rod ends, tired bushes, a bent wishbone or a failing top mount can all pull the geometry out of alignment, and no amount of pressure checking will fix that.

Four-wheel alignment checks are quick and relatively inexpensive at most tyre bays, and many will offer a free check. If you have just replaced tyres, it is worth having the alignment done at the same time. There is little point spending several hundred pounds on new rubber only to have it scrubbed away in an avoidable pattern. Ask for a printout of the before and after readings so you can see exactly what was adjusted.

Keep an eye out for other clues too. If the car pulls to one side on a flat road, the steering wheel sits off-centre when driving straight, or you hear knocking over bumps, get the suspension inspected sooner rather than later. Small fixes now are much cheaper than a set of tyres plus the repair.

A simple monthly routine that pays for itself

Set a reminder on your phone for the first weekend of every month. Check all four tyres and the spare with a reliable gauge, topping up at a garage or with a foot pump at home. While you are knelt down there, run your hand around each tread and feel for uneven patches, and check the tread depth. The legal minimum in the UK is 1.6mm across the central three-quarters of the tread, but most experts suggest replacing at 3mm for safe wet-weather performance.

Also look for cuts, bulges, nails and stones lodged in the grooves, and check that valve caps are fitted — they keep dirt out and reduce slow leaks. If one tyre keeps losing pressure, get it looked at rather than simply topping it up every week. A slow puncture or a corroded alloy rim can be sorted cheaply.

It is the least glamorous job on the car, but five minutes with a pressure gauge will improve your fuel economy, keep your tyres lasting longer and give you a car that feels sharper and safer on every journey.