How to change a car tyre safely

Before you touch anything: park and prepare

A puncture rarely arrives at a convenient moment, and in the West Country it often turns up on a single-track lane with a hedge pressed against the passenger door. Get the car somewhere safe and flat before you start — a lay-by, a garage forecourt or a wide verge. On a busy road, pull as far left as you can, switch on the hazard lights and put on a hi-vis vest before you open the door. Passengers should wait behind the barrier, well away from the traffic. Once you have stopped:

• Apply the handbrake firmly and put the car in first or reverse, or Park for an automatic.
• Chock the wheel diagonally opposite the one you are changing — a spare wheel, a lump of firewood or a stout stone will do.
• Switch off the engine and, if you carry one, place a warning triangle at least 45 metres behind the car.
• Find the jack, wheel brace, locking wheel nut key and spare before you get down on your knees.

Loosen the wheel nuts before the car goes up

This is the step most drivers skip, and it is the one that ruins the job. With the weight of the car still on the tyre, the nuts will move; once the car is in the air, turning the brace simply spins the wheel. Push down anticlockwise with a steady, firm force — a gentle bounce with your foot is fine, but never kick at it. Most cars use 17mm, 19mm or 21mm nuts, and locking nuts need their key, which usually lives in the boot with the jack. Keep it in the glovebox afterwards so you are never hunting for it at the roadside.

Loosen each nut about a quarter turn, no more. If one refuses to budge, try a longer bar, a squirt of penetrating oil left for a few minutes, or a firm tap on the brace with a mallet. On cars that have run alloys through a coastal winter, a little corrosion around the nut seats is entirely normal.

Jacking the car without drama

Your handbook shows the jacking points, and they matter. On most cars they are reinforced sections of the sill, marked by a notch or small arrow, roughly a hand's width behind the front wheel or ahead of the rear. Feel for the metal seam and seat the jack's groove firmly on it. Put the jack under a suspension arm, the sump or a plastic sill cover and you risk expensive damage — or the car coming down while you are beneath it.

Wind the jack up steadily until the tyre is just clear of the ground, two or three centimetres at most. A scissor jack is built for exactly this job, but it is not a workshop tool, so treat it gently. Never put any part of your body under a car supported only by a jack. Slide the spare wheel under the sill as a safety net. On soft ground — and there is plenty of it on Devon and Somerset verges — put a flat board under the jack's foot so it cannot sink.

Swapping the wheel and tightening it properly

Remove the loosened nuts and put them where they cannot roll into a drain — a mug, a tin or your pocket. Grip the wheel at nine and three o'clock, brace your knees and pull it towards you; a firm nudge with your foot at the bottom edge often helps. Wheels are heavier than they look, so lift with your legs, not your back.

Lift the spare into place, lining up the bolt holes with the studs. With the wheel held flat against the hub, fit the nuts by hand until they are finger-tight, working diagonally across the wheel rather than round in a circle. This star pattern is what stops the wheel seating crookedly. Lower the jack until the tyre touches the ground but the full weight is not yet on it, then tighten the nuts firmly in the same star pattern. Lower the car completely and give each nut a final, solid tighten.

Space savers, pressures and the first thirty miles

If your spare is a skinny space saver, read the sidewall before you set off. Most are rated for a maximum of 50mph and around 50 miles, and many need 60psi — far more than a normal tyre. Avoid motorways, brake gently, and do not fit one to a driven axle if the handbook says otherwise. A full-size spare can be driven normally, but check its pressure first: spares lose air slowly over years and are often forgotten until the day they are needed.

Whichever you have, stop after about 30 miles and check the nuts with the wheel brace. A typical car wants around 110Nm, which is a firm push on a standard brace, not a leap on a scaffold pole. If you own a torque wrench, use it. Book the punctured tyre in for repair or replacement within a few days, and remember that a tyre with sidewall damage or a puncture near the shoulder should not go back on the car.

West Country conditions worth knowing

Our roads are hard on tyres and on the kit that changes them. Salt-laden air along the Cornwall and Devon coast corrodes locking wheel nuts and alloy seats, so a smear of grease on the studs and a twice-yearly check of the key will save you a miserable afternoon. Potholes on moorland roads and the lanes around Exmoor and Dartmoor regularly buckle wheels and pinch sidewalls; if the steering shakes after a knock, get the wheel looked at.

Steep gradients and narrow lanes also mean you should think before you stop. A jack on a slope is dangerous, and a wheel on a banked, grassy verge may look supported when it is not. Drive on to a flat farm entrance, a passing place or a village car park if one is within reach — a slow, noisy mile on a soft tyre is far cheaper than a crushed sill. Finally, keep a torch, gloves and a waterproof in the boot through winter. This is a part of the country where the weather turns quickly, and changing a wheel in the dark, in the rain, on the A39 is a job you want finished in twenty minutes, not forty.