Summer Heatwave Tips for Lorries: Keeping Tyres, Engines, and Drivers Cool

October 06, 2026

A 30°C afternoon does more to a lorry than make the cab uncomfortable. The asphalt under the wheels gets hotter still, tyre pressures climb, the cooling system works flat out, and the driver spends eight hours in a glass box with the sun on one side. Most summer breakdowns are not freak failures. They are small things that were fine in April and are not fine in July.

None of this needs a workshop visit before every run. It needs a routine that changes with the season, and a driver who knows what to look at before the day gets hot.

Tyres: pressure, heat, and the mistake most drivers make

As a tyre rolls, it flexes, and flexing makes heat. As it heats, the air inside expands and the pressure climbs. On a long run in high temperatures, that rise is normal and expected. What is not normal is a tyre that runs hotter than the others, or one that has been quietly under-inflated for weeks.

Under-inflation is the real enemy in summer. A soft tyre flexes more, heats faster, and is far more likely to fail at speed. Over-inflation gives a harsher ride, uneven wear and less grip. Both problems start with pressure checked at the wrong time or not at all.

Check pressures when the tyres are cold, before the day's first run, and set them to the figures for your axle loads, not to a number someone mentioned in a yard. Never bleed air out of a hot tyre to bring the gauge down to the "correct" reading. You will simply send it out under-inflated for the rest of the day.

A quick tyre routine for hot days

Pressures checked cold, on all axles, including the trailer and any spare.
Tread depth and even wear across the face. A shoulder worn thin tells you something about alignment, not just about the tyre.
Sidewalls inspected for cuts, bulges and heat cracking. A bulge means the casing is damaged internally and the tyre should come off.
Valve caps on and valve stems in good condition. A slow leak is a slow leak whatever the weather, and heat makes it worse.
Wheel nuts checked for torque and for signs of movement or rust streaking, which can point to a loosening wheel.
After a run, touch the hubs and tyres by hand, carefully, or use a heat gun. One tyre noticeably hotter than its pair is telling you to stop and look.

Cooling system: coolant, airflow, and the cap nobody checks

Summer is when a cooling system that was marginal in winter finally gives up. Check the coolant level only when the engine is cold. Opening a hot system is a scalding risk, and it tells you nothing useful anyway.

Use the coolant type your manufacturer specifies, and do not mix different chemistries to top up. If you are unsure what is in the system, that is a job for the workshop. A correct mix of coolant and water raises the boiling point, protects against corrosion and keeps the water pump and radiator healthy. Topping up with plain water dilutes all of that.

Airflow matters as much as fluid. Radiator and charge-cooler fins clogged with dust, straw, insects and road grime cannot transfer heat. Blow them out with compressed air from the engine side, gently and in the direction of the fins. A pressure washer at close range will fold the fins flat and make the problem permanent.

Then check the parts that hold it all together: the pressure cap, the hoses for softness and cracking, the clamps, the fan and its viscous coupling or electronic control, the belts and tensioners. A fan that is not engaging at low speed will only show itself in traffic on a hot afternoon, which is exactly when you need it.

Under the bonnet: oil, belts, batteries and filters

High ambient temperatures are hard on lubricants. Engine oil that is already past its interval will thin further and work less effectively, and the same logic applies to gearbox and differential oil on heavily loaded runs. Stick to service intervals, and if you do a lot of stop-start work in the heat, bring the oil change forward rather than stretching it.

Batteries are often described as a winter problem, but heat is what kills them. High temperatures accelerate internal wear and corrosion, and the failure usually shows up on the first cold morning months later. Check terminals for corrosion, security and a clean, tight connection.

Air filters deserve a look too. Dry, dusty summer roads load them faster than damp winter ones. A restricted filter costs fuel, and on a hot day it works the engine harder than it needs to.

Air conditioning and the cab: comfort is a safety system

Treat the air conditioning as safety equipment, not a luxury. A driver who is too hot loses concentration, gets irritable and makes worse decisions. Get the system checked before the season, not on the day it fails.

Common sense goes a long way here:

Change the cabin filter. A blocked one cuts airflow and lets dust and pollen through.
Check refrigerant charge and look for leaks rather than simply topping up. Repeated top-ups mean the gas is going somewhere.
Aim vents at the body, not directly at the face, and avoid a constant blast of cold air on the neck and shoulders.
Park in shade when you can, use a windscreen shade, and air the cab out before setting off.
If you run a fridge or refrigerated trailer, remember the condenser needs clean airflow just like the engine radiator.

Looking after the driver: heat stress is a real risk

The cab can be the hottest place on the job. Heat builds through the windscreen, and on a long shift the effects creep up quietly: headache, tiredness, dizziness, cramp, feeling sick. If you notice those signs in yourself or a colleague, get out of the heat, cool down and drink water. If symptoms are severe, or do not settle quickly, seek medical advice rather than pushing on.

Practical habits that help:

Drink water steadily through the day rather than large amounts all at once. Keep a bottle within reach.
Go easy on strong coffee and energy drinks, which can make dehydration worse.
Eat lighter meals. Heavy food plus heat plus a long drive is a poor combination.
Plan breaks around the hottest hours, and take them somewhere shaded rather than on hot tarmac.
Wear light, loose clothing and keep a spare shirt. A damp, cool cloth on the neck or wrists helps more than people expect.
Use the bunk sensibly on rest periods: parked in the sun, a cab becomes an oven within minutes.

Work within your permitted driving and working hours, and be honest about how the heat is affecting you. Fatigue rules exist for good reason, and heat makes fatigue arrive sooner.

A summer routine worth keeping

Before the first hot run of the week, walk the vehicle with the season in mind: cold tyre pressures, coolant level, hoses, belts, battery terminals, a look at the radiator and air conditioning. Ten minutes, and most of it you would do anyway.

During the day, watch the gauges and the road: coolant temperature creeping higher on a climb, one tyre running hotter than the others, a cab that will not cool down. Stop and investigate while it is still a small problem.

None of this is complicated. It is just the difference between a lorry that coasts through August and one that spends it in the yard.

Photo: Boris Hamer / Pexels