Tyre pressures when you are loaded up or towing
6 min readBy Wheel Fit
The short answer The placard in your door shut almost always lists two sets of pressures — normal and fully laden. Most drivers only ever use the first. The laden figures matter most on the holiday run with a full boot, a roof box and four people, which is exactly the journey people set off on without checking.
Under-inflation is the single most common tyre fault, and it gets worse the more weight you add. A tyre carrying more load at the same pressure flexes further, runs hotter and wears its shoulders — the same failure mode as running it flat, just slower.
Where to find the laden figures
The placard is usually in the driver's door shut, sometimes inside the fuel filler flap or in the glovebox. It typically shows a small table: tyre size down the side, and columns for something like "up to 3 occupants" and "fully laden".
Not the number on the tyre The figure moulded into the sidewall is the tyre's maximum pressure, not the correct pressure for your car. Always use the vehicle placard or handbook. Correct tyre pressure covers this in full, including why you must check cold.
When to switch to laden pressures
| Situation | Use |
|---|---|
| Daily driving, one or two people, light boot | Normal pressures |
| Full car of passengers plus luggage | Laden pressures |
| Roof box or roof rack loaded | Laden pressures |
| Towing a caravan or trailer | Laden pressures on the towing vehicle, usually rear especially |
| Van carrying tools or stock | Laden — see van tyres vs car tyres |
| Long motorway run at sustained speed | Check the handbook — some specify a higher figure |
Towing: the nose weight goes on the rear axle
When you hitch up, the downward force at the towball transfers onto the tow vehicle's rear axle — and it also lifts weight slightly off the front. That is why laden pressures for towing usually raise the rear figures more than the front.
The trailer or caravan has its own pressures, which are generally much higher than a car's and are specified by its manufacturer, not by the tyre. Do not guess these; an under-inflated caravan tyre at motorway speed on a hot day is a well-known failure.
What under-inflation under load actually does
- Heat. The sidewall flexes further on every rotation, and that flexing generates heat. Heat is what destroys tyres.
- Shoulder wear. The tread contacts the road at its edges rather than evenly — see uneven tyre wear.
- Longer braking distances, on a car that is already heavier and takes longer to stop.
- Vague, wallowy handling, especially noticeable when towing.
- More fuel used — increased rolling resistance, on the journey where you are covering most miles.
Do not forget to change them back
Over-inflation is a milder fault than under-inflation, but it is still a fault. Running laden pressures on an empty car gives a harsher ride, reduces the contact patch and wears the centre of the tread.
The practical habit: set laden pressures before you load up, and reset them when you unload. If you have indirect TPMS, reset the system after each change so it calibrates to the new figures — the TPMS warning light explains why that matters.
Check the load rating too, not just the pressure
Pressure is only half of it. Every tyre has a load index setting the maximum weight it can carry, and pumping a tyre up does not raise it. If you regularly carry heavy loads, check that the tyres fitted actually meet the vehicle manufacturer's specified load index.
Load index and speed rating explained covers how to read it, and why fitting below specification is a genuine safety issue rather than a technicality.
Common questions
- How much higher are laden pressures?
- Commonly a few PSI on the front and rather more on the rear, but it varies widely by vehicle. Use your placard rather than a rule of thumb.
- Can I just run laden pressures all the time?
- You can, and some drivers do for the convenience. The trade-off is a firmer ride and faster centre wear. It is safer than running under-inflated, but it is not free.
- Do I check pressures hot after loading?
- Set them cold, before you set off. A warm tyre reads higher and letting air out to hit the cold figure leaves you genuinely under-inflated once it cools.
- My car has no placard — where else?
- The handbook, and often the fuel filler flap. If the car has non-standard wheel sizes, the placard may not cover them; ask when the tyres are fitted.
Before a big trip
If you want the tyres checked properly before a holiday or a tow, we can do it at your home — pressures, depths, condition and age across all four, plus the spare if you carry one. Call 07989 606060.
