An over-inflated tyre is one running above the recommended pressure. It is less common than under-inflation, often the result of inflating to the tyre's maximum sidewall figure by mistake, or topping up warm tyres to a cold target. It brings its own set of problems.
The signs
Too much pressure shows up in how the car rides and how the tyres wear:
- A hard, jittery ride that thumps over bumps and expansion joints
- Nervous, skittish grip, as less rubber meets the road
- Over time, wear concentrated in the centre of the tread, with the edges still healthy
As with low pressure, a gauge check on cold tyres against the recommended figure is what confirms it.
Why it is a problem
An over-inflated tyre bulges slightly in the middle, so its contact patch shrinks to a narrow central strip. That smaller patch is the root of the issues:
- Less grip and longer braking, because there is less rubber on the road
- Centre wear, as the middle of the tread carries more than its share of the load
- A harsh ride, since a hard tyre absorbs less of the road
- Greater vulnerability to impact damage: a taut, hard tyre is more easily split or made to bulge by a pothole or kerb than one at the correct pressure, which can mean an early replacement
The fuel myth
It is sometimes said that higher pressure saves fuel. The effect is real but tiny, and the trade is a poor one: a small gain in rolling resistance comes at the cost of grip, braking, comfort and tread life. The recommended pressure already balances economy against everything else, so there is nothing to gain by exceeding it.
What to do
Release air down to the correct cold pressure using the pin in the valve, checking with a gauge as you go. If the tyres were only warm-high, a few PSI over after a drive, that is normal and needs no action, since the figure is a cold one.
From the workshop: most over-inflation we see comes from someone reading the maximum off the sidewall and aiming for that. The car ends up bouncy, the middle of the tread wears out early, and the grip suffers, all for a number that was never meant to be the target.
Sources and accuracy. The effects described here reflect manufacturer and motoring-body guidance at the time of writing. Anything safety-critical should be confirmed against current official guidance. If anything here looks wrong, get in touch and we will check it and put it right.
Common questions
How can I tell if my tyres are over-inflated?+
The ride feels hard and jittery over bumps, grip can feel nervous, and over time the centre of the tread wears faster than the edges. A gauge check on cold tyres against the recommended figure is the way to confirm it.
Are over-inflated tyres dangerous?+
They can be. Too much pressure shrinks the contact patch, which reduces grip and lengthens braking, and a harder tyre is more easily damaged by potholes and kerbs. It also wears unevenly, so it is bad for safety, comfort and tyre life alike.
Does higher pressure improve fuel economy?+
Only marginally, and not worth it. A little extra pressure slightly cuts rolling resistance, but going above the recommended figure trades away grip, braking, comfort and even tread life for a tiny saving. The recommended pressure is the sensible balance.
Where does an over-inflated tyre wear?+
In the centre. An over-inflated tyre bulges slightly in the middle of the tread, so the centre carries more of the load and wears faster than the edges. That central wear band is the tell-tale sign of running too much pressure.