Why you should never drive with an underinflated tyre

Under-inflated tyre: definition and causes

One Under-inflated tyre is a tyre with pressure lower than the manufacturer's recommendation. Even a moderate drop (for example -0.2 to -0.4 barcan already impact the vehicle's behaviour, especially at high speed, when cornering or in the rain.

Why is the pressure dropping?

• Natural loss A tyre gradually loses air over time.
• Temperature The cold causes the pressure to drop (seasonal variation).
• Micro-leak valve, rim, bead, or small puncture.
• Charge/usage Motorway journeys, loaded vehicle, trailer.

Safety: braking distances and road holding degraded

caractéristique générale du véhicule. contact surface with the road and the tyre's rigidity. When a tyre is underinflated, it sinks more, deforms, and responds less precisely to demands.

Consequences for driving

• Less effective braking The chassis deforms, adhesion becomes less stable, especially under heavy braking.
• Deteriorated road holding : softer steering, less precise cornering lines.
• Increased risk in the rain fewer chewing movements, less constant water evacuation, more unpredictable behaviour.

To keep in mind A tyre with the correct pressure improves stability, driving precision and safety margins in emergency situations.

2) Overheating: the risk of failure increases

La principale danger d'un pneu sous-gonflé, c'est la Overheating. When driving, the tyre deforms with each rotation. If it lacks pressure, it deforms much more, which generates more heat.

Pourquoi le réchauffement est-il un problème ?

• The heat weaken the internal structure of the tyre (carcass, plies, sidewalls).
• The risk of delamination or deformation increases over long distances.
• At high speeds (motorway), the temperature can rise quickly and become critical.

In plain English: the more underinflated the tyre is, the hotter it gets, and the more the risk of breakdown (or failure) increases.

3) Wear and tear: tyres to replace much sooner

An under-inflated tyre wears out faster, often unevenly. The tyre leans more on the Shoulders (tyre shoulders), which accelerates wear on the sides.

Typical signs of under-inflation wear

• Smoother shoulders the centre of the tyre.
• Aspect “eaten” on the edges, especially on the front.
• Deformation of the side or a “soft tyre” sensation.

Result: you are replacing your tyres earlier, sometimes well before reaching uniform wear.

4) Fuel consumption: you pay more at the pump

Un pneu sous-gonflé augmente la consommation de carburant. rolling resistance. The engine has to work harder to maintain speed, which results in a Fuel overconsumption (or a decrease in range on an electric/hybrid vehicle).

Why does rolling resistance increase?

• The tyre crushes and deforms further.
• The ground contact area changes, with more mechanical “losses”.
• Heat and internal friction increase.

Good reflex: A simple monthly tyre pressure check can help reduce fuel consumption and extend the life of your tyres.

How to recognise an under-inflated tyre

Certain signs are visible or felt, but the ideal remains to measure the pressure with a pressure gauge.

• TPMS indicator light (if your car is equipped with it): low tyre pressure warning.
• Less precise direction or a feeling of light-headedness.
• Vehicle which “pulls” slightly to one side.
• Bearing noise unusual or vibration.
• Tyre visually lower that another (notable difference).

Attention: A tyre can be under-inflated without looking “flat”. Only a measurement can confirm.

What pressure to put in your tyres

The Recommended pressure depends on the vehicle, the tyre size and the use (loaded, motorway, etc.). You will generally find it:

• on the label in the’door frame driver,
• in the Fuel trap (depending on models),
• in the manual of the vehicle.

Practical advice: check the pressure cold (before riding, or after a few kilometres at low speed). A warm tyre will show a higher pressure and can distort the adjustment.

Good practice: check and re-inflate correctly

How often should I check the pressure?

• Once a month Minimum.
• Before a long journey (motorway, holiday).
• When the temperature changes strongly (winter/spring).
• After a shock : potholes, pavements.

Simple steps for inflating

1. Identify the target pressure (front/rear, and “loaded” version if needed).
2. Measure when cold, then adjust using a compressor.
3. Control also the Spare wheel if you have one.
4. After re-inflating, check for leaks if the pressure drops quickly.

Tip: a steady drop in pressure on a single tyre can indicate a micro-perforation or a problem with the valve. Have it checked as soon as possible.

FAQ: Under-inflated tyres