First, Get Yourself Safe

A puncture rarely picks a convenient spot. It might happen halfway up a steep Sheffield hill, on the ring road at rush hour, or somewhere along the Snake Pass with nothing but moorland either side. Before you even think about the jack, your priority is making sure you are not standing in a live traffic lane. If the tyre lets go on a motorway or a fast dual carriageway, try to roll onto the hard shoulder and, if you can, get the car as far from the traffic as the barrier allows. Put your hazard lights on immediately.

Once you have stopped, do the following before you open the boot:

• Apply the handbrake firmly and leave the car in first or reverse gear, or in Park if it is an automatic.
• Switch on your hazard warning lights and, if you are on a road rather than a motorway, put on a high-visibility vest if you carry one.
• Ask passengers to get out on the side away from traffic and stand well behind the barrier or up on the verge — never in the car while it is jacked up.
• If you are on a smart motorway, note where you are and use the emergency phone rather than trying to change the wheel yourself. It is genuinely not worth the risk.

On an ordinary A-road or a residential street in somewhere like Hillsborough or Woodseats, your job is easier, but the same rules apply. Choose a flat, firm piece of ground if you have any choice at all. Jacking a car on a slope is how people get hurt.

Know What Is Actually in Your Boot

Have a look before you need it. Most cars come with a scissor jack, a wheel brace, a locking wheel nut key if the alloys are fitted with one, and either a full-size spare, a space saver, or — increasingly — a tin of sealant and a small compressor instead of any spare at all. If you have the foam kit, this guide is not for you; you cannot physically change a wheel that is not there. Read the sealant instructions instead, and remember they usually only work on small tread punctures, not sidewall damage.

Two things catch people out. The first is the locking wheel nut key, which is often tucked in a foam holder near the jack or in the glovebox. Without it, you are going nowhere. The second is a space saver, which looks like a toy and comes with a strict speed limit, usually 50 mph, and a range limit of around 50 miles. Check the sidewall for the exact figures.

Loosen the Nuts Before You Lift

This is the step that trips up more people than any other. The wheel nuts must be cracked loose while the tyre is still on the ground and the weight of the car is holding it in place. Once the car is in the air, the wheel will simply spin.

• Fit the wheel brace onto the first nut and turn it anti-clockwise to loosen. If it will not budge, stand on the brace — with the car on flat ground and the handbrake on, that is a legitimate technique — or use a longer bar if you have one.
• Loosen each nut about a quarter to a half turn. Do not remove them yet.
• If the nuts are rusty or the car has recently been serviced with an air gun, expect a fight. A squirt of penetrating oil and a few minutes' wait can help.

Before you raise the car, chock the wheel diagonally opposite the one you are removing. A brick, a lump of wood, or even the spare wheel laid flat will do. This stops the car rolling while it is up in the air.

Jacking the Car Correctly

Find the jacking points. These are almost always the reinforced seams along the sill, marked by small notches or arrows, and they are described in your handbook — keep it in the glovebox for exactly this reason. Position the scissor jack under the correct point, then raise the car slowly until the flat tyre is a couple of inches clear of the ground.

Two safety habits worth building for life:

• Never put any part of your body under a car supported only by a jack.
• Once the wheel is off, slide it flat under the sill as a back-up. If the jack slips, the car lands on the wheel, not on your hand.

If the ground is soft — a verge after rain, or a gravel driveway — put a flat piece of wood or a folded mat under the jack base so it does not sink.

Swapping the Wheel

With the car lifted, undo the loosened nuts by hand and lift the wheel straight off. It can be heavy, especially a 17-inch alloy, so lift with your legs and keep your back straight. Set it down flat, not face down where it can roll.

Line up the spare with the studs or bolt holes and lift it into place. If your car uses bolts rather than studs, a helpful trick is to thread the top bolt in first by hand to take the weight. Push the wheel flush against the hub, then fit the nuts finger-tight in a star pattern — opposite nut, then across — so the wheel sits square. Do not tighten fully yet.

Lowering and Final Tightening

Lower the jack until the tyre touches the ground but the full weight of the car is not yet on it. Now tighten the nuts properly, again in a star pattern, as hard as you reasonably can with the brace. Fully lower the jack and remove it, then give every nut one last check. A wheel that works loose after a few miles is a genuinely frightening thing, so take the extra thirty seconds.

Stow the tools, the jack and the damaged wheel, and put your hazards off. If you are running a space saver, keep your speed down and head for the nearest tyre bay — plenty of drivers around South Yorkshire keep a note of one on their usual routes. Book a proper torque check within 50 miles, and ask them to look at the punctured tyre too. Many tread punctures can be repaired for a fraction of the cost of a new tyre, provided the sidewall is undamaged and the hole is not too close to the shoulder.

Finally, a word about practice. Doing this once in daylight on a dry driveway, when nothing is at stake, turns a stressful roadside job into a twenty-minute inconvenience. It is one of the best hours you will ever spend on your car.