Sustained motorway speed and the heat it builds are exactly what expose a weak tyre, so a quick check before you set off can catch a problem before it becomes a breakdown. Look at tread, pressures and condition while you're still on the drive, where any problem is a quick fix rather than a hard-shoulder emergency. Here's the checklist worth running.
Why motorways test tyres
A long motorway run combines high speed, sustained load and heat, hour after hour. A tyre that's marginal, under-inflated, worn or carrying hidden damage, is far more likely to fail under those conditions than on short local trips, see blowout causes. That's why pre-journey checks matter most before exactly this kind of drive.
The pre-journey checklist
TyreSafe, the UK tyre safety charity, sums the essentials up as the ACT check: Air pressure, Condition and Tread depth. Run through all three before a long run.
- Tread: the 20p test on all four tyres, including inner edges. The legal minimum is 1.6mm across the central three quarters.
- Pressure: set cold to the right figure, see tyre pressure.
- Condition: look all round for cracks, bulges and embedded objects.
- Spare: check the spare or repair kit is ready.
Pressures for a loaded car
A long journey often means a full car. A loaded car needs the higher laden pressure on your door placard, or the tyres run effectively under-inflated, which builds heat exactly when they're working hardest. Setting the laden figure before a fully packed motorway trip is one of the most effective things you can do to prevent a blowout.
On the journey
Take a break roughly every two hours. It keeps you alert and lets the tyres cool, and it's a chance to glance at them at the services. If a tyre looks low or the car feels different, stop and check rather than pressing on.
A new vibration through the wheel, a pull to one side or a tyre pressure warning are all reasons to leave at the next services rather than push on to your destination. If anything does go wrong, follow motorway breakdown safety.
How much tread is enough for a long trip?
Legal is 1.6mm, but for a long, fast, possibly wet journey you want a comfortable margin above it. The legal minimum is 1.6mm across the central three-quarters of the tread, around the whole circumference, and each tyre below that risks a fine of up to £2,500 and three penalty points.
Grip in standing water falls away well before the legal limit, which is why TyreSafe and most safety bodies suggest planning a replacement from around 3mm.
| Tread depth | What it means for a motorway trip |
|---|---|
| 4mm or more | Plenty of margin. Check pressures and condition and go. |
| 3mm | Still safe, but wet-weather grip is falling. Plan a replacement soon. |
| 2mm | Marginal for a long, wet run. Replace before a big trip if you can. |
| 1.6mm or less | Illegal. Do not set off on it. |
A 20p coin in the main grooves gives you a quick read, and a cheap tread gauge gives you the number. Check the inner shoulder as well as the middle, because misalignment often wears one shoulder, frequently the inner one and that edge is the one you cannot see from standing beside the car.
If one tyre is well down on its partner across the axle, replace them as a pair on that axle where possible.
The walk-round checklist
Ten minutes on the drive covers the tyre items that matter on a long run. Do it a few days before rather than the morning you leave, so there is time to deal with a problem.
| Item | What to check |
|---|---|
| All four tyres | Tread with a 20p or gauge, pressures cold against the door placard, cracks, bulges, nails. |
| Spare or kit | Spare inflated to its own (often higher) pressure; sealant kit in date and the compressor working. |
| Locking wheel nut key | In the car and not in the garage drawer. Without it a wheel cannot come off; see locking wheel nut removal. |
| Jack and brace | Present and usable, even if you would only use them off the motorway. |
| TPMS | Warning light off. If you have adjusted pressures, reset the system if your car needs it. |
| Emergency kit | Hi-vis, torch, warm layer, water, phone charger, breakdown cover details. |
| Tyre size | Photograph the sidewall so you can read the size to a fitter if you need one. |
Two of these are easy to overlook. A spare can be years old and soft, because a wheel you cannot see is easy to forget, so read spare wheel maintenance. And the locking wheel nut key is the one item that turns a ten-minute wheel change into a wait for a specialist.
Towing, roof boxes and heavy loads
Extra weight changes the pressure you need, the way the car handles and the speed you may legally drive. A roof box, a full boot and four passengers together can put a family car close to its maximum permitted weight, and the tyres carry all of it.
- Pressures: use the laden figure on the door placard or in the handbook, on the rear axle especially. Set it cold, before you load the car if you can.
- Load index: the number after the size on the sidewall must cover your loaded weight. This matters most on vans and large SUVs.
- Trailers and caravans: the trailer tyres need their own pressure and age check, and caravan tyres often fail on age rather than tread.
- Speed: a car towing a trailer or caravan is limited to 60mph on motorways and dual carriageways under the national speed limits, which also keeps the tyres cooler.
A roof box raises the centre of gravity and adds wind resistance, so leave more room to brake and slow earlier for bends. Stop after the first 20 or 30 miles to check that the box and any straps are still tight, and glance at the tyres while you are there.
If a tyre fails on the way
Get left, get out, get behind the barrier, and then call for help. The Highway Code's motorway rules are the framework: ease off rather than braking hard, get to the hard shoulder or an emergency area, leave by the passenger side and stand behind the barrier with everyone, including pets.
On a smart motorway with no hard shoulder, aim for an orange emergency area. If you are stuck in a live lane and cannot get out safely, keep your seatbelt on, put the hazards on and call 999.
From the hard shoulder or an emergency area, call National Highways on 0300 123 5000 or use the SOS phone. Their traffic officers can help get you to a safer place. Nobody should change a wheel on the hard shoulder or in a refuge area, and we never fit there.
Once you are at a services, a retail car park, if the operator agrees, or a side road off the motorway, a mobile fitter can replace the tyre where the car stands.
If the tyre is losing pressure slowly and the car still drives normally, leaving at the next junction or services at reduced speed is usually safer than stopping in a live lane.
If it is flat or has blown, stop as soon as you safely can; driving on a flat destroys the tyre and can wreck the wheel.
Set off on good tyres
If your check finds a worn or damaged tyre, we can replace it at your home or workplace. Call with the tyre size and we give you the price and an arrival time on the call; book early if you are travelling soon.
