How to Change a Tire
Tech & Car · How-to · 6 min read
How to Change a Tire
Most people do this once, at night, in the rain, having never practised. It is not hard, but the order matters and two of the steps are the ones that go wrong. Here is the whole thing, plus the part nobody mentions until you are already stuck.
Before you touch anything
Get the car off the traffic lane if you possibly can — a flat rim is cheaper than being hit. Hazards on, handbrake on, park in gear (or P). On a slope, wedge something behind the wheel diagonally opposite the one you are changing.
Take the spare, the jack and the wrench out of the boot before you lift the car. Reaching into a boot while the car is on a jack shifts weight you did not plan for.
The order
- Loosen the lug nuts while the wheel is still on the ground. A quarter turn each, no more. If you lift first, the wheel spins and you cannot break them loose. This is the step people skip.
- Find the jack point. There is a reinforced pinch weld behind the front wheel and ahead of the rear one — your manual has the diagram. Jacking on the floor pan or a suspension arm bends things that cost more than the tyre.
- Lift until the tyre is about an inch clear of the ground. No higher.
- Remove the nuts the rest of the way and pull the wheel straight off. Put it under the sill as a backstop — if the jack fails, the car lands on the wheel instead of on you.
- Mount the spare, hand-tighten the nuts in a star pattern, opposite to opposite. Never go around the circle in order.
- Lower the car until the tyre just touches, then torque the nuts properly in the same star pattern. Then lower fully.
Never get any part of you under a car held up by a jack. A jack is for lifting, not for holding.
How tight should the lug nuts be?
Tighter than hand-tight, looser than you think. Most passenger cars land between 80 and 100 lb-ft; your manual or the sticker in the door jamb has the number. Guessing goes wrong in both directions — too loose and the wheel works its way off over the next fifty miles, too tight and you stretch the studs or warp the brake disc, and the next person to get a flat cannot break the nuts loose at the roadside at all.
This is the one step on the list where a tool actually changes the outcome. A digital torque adapter ($89.99) sits between the ratchet you already own and the socket, and buzzes when you hit the number you set. It is small enough to live in the glovebox, which is where it needs to be, not in the garage.
The part nobody warns you about: the spare is probably flat
Spares lose pressure sitting in the boot. A full-size spare wants the same pressure as the others; a compact "donut" usually wants 60 PSI, which is far higher than a normal tyre and almost never what you will find in there after two years.
So the sequence that actually happens is: change the wheel, drive off, and discover the spare is soft. A cordless tire inflator ($99.99) fixes that at the roadside — set the target pressure, press start, it stops on its own. It is cordless, so there is no cable to run to the cigarette lighter while you are half on the verge, and the built-in light matters more than it sounds when the flat happens after dark.
It is also the tool that means you sometimes do not have to change the tyre at all. A slow puncture that is losing a few PSI a day will often hold long enough, re-inflated, to get you to a garage in daylight.
What PSI should my tires be?
Not the number on the tyre — that is the maximum the tyre can take, not what your car wants. The right figure is on a sticker inside the driver door jamb, and it is often different front to rear. Check when the tyres are cold, before you have driven on them; a warm tyre reads several PSI high and you will end up under-inflated.
How often should you check?
Monthly, and before any long drive. Tyres lose roughly 1 PSI a month on their own, and about 1 PSI for every 10°F the temperature drops — which is why the warning light comes on across half the country on the first cold morning of autumn, on tyres that are visibly fine.
After the change
- Re-torque the lug nuts after 50 to 100 miles — they settle
- A donut spare is rated for about 50 mph and 70 miles. It is a way to reach a garage, not a tyre
- Put the flat back in the boot the right way up so the wheel weights stay put
What to keep in the car
- Cordless Tire Inflator 150 PSI — preset pressure, auto shut-off, LED work light
- Digital Torque Wrench Adapter — 1/4", 3/8" and 1/2" drive, buzzes at your target
- OBD2 Scanner — for the light that comes on afterwards and is unrelated
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