Tyre pressure has a direct, measurable effect on how much fuel you use. Soft tyres make your engine work harder, and that quietly adds to every fill-up.
Quick answer: Keeping your tyres at the correct pressure can improve fuel economy by a few percent and helps them last longer. Check them cold, at least once a month, against your car's recommended figures. Then find the cheapest fuel near you to save even more.
How tyre pressure affects fuel economy
Tyres are the only part of your car touching the road, and they're constantly flexing as they roll. That flexing is called rolling resistance, and the engine has to overcome it to keep you moving.
When a tyre is underinflated:
- More of its surface is squashed against the road.
- It flexes more and generates more friction and heat.
- Rolling resistance rises, so the engine burns more fuel to maintain speed.
The effect isn't dramatic on any single journey, but it's constant. A car running on soft tyres all year is quietly throwing money away on every mile.
How much fuel do underinflated tyres waste?
As a rough guide, fuel economy drops by around 1% for roughly every few psi below the recommended pressure across all four tyres. The exact figure varies by car and tyre, but the trend is consistent: the softer the tyres, the worse the mpg.
| Tyre condition | Effect on rolling resistance | Effect on fuel economy |
|---|---|---|
| Correct pressure | Optimal | Best for your car |
| Slightly underinflated | Higher | A small mpg loss |
| Significantly underinflated | Much higher | A noticeable mpg loss |
| Overinflated | Slightly lower | Tiny gain, worse grip and wear |
It's not just fuel, either. Underinflated tyres wear unevenly, overheat, and can fail — so correct pressures are a safety and money issue at once.
Finding the correct tyre pressure for your car
You don't need to guess. The right figures are printed somewhere on your car, usually in one of these places:
- A sticker inside the driver's door pillar.
- Inside the fuel filler flap.
- In the owner's handbook.
A few things to watch for:
- Front and rear pressures may differ. Many cars run higher pressures at the back.
- There's often a "laden" figure. Carrying passengers, luggage or towing usually calls for higher pressures.
- Motorway driving sometimes has its own recommended pressure for sustained high speed.
- Pressures are given in psi or bar — make sure your gauge matches.
Why "correct" beats "high"
It's tempting to overinflate to chase a little extra mpg. Resist it. Overinflated tyres reduce the contact patch, which hurts braking and grip, gives a harsher ride, and wears the centre of the tread prematurely. The small fuel gain isn't worth the trade-off. The manufacturer's figure is the sweet spot between economy, safety and tyre life.
How to check tyre pressure properly
Getting an accurate reading matters, so follow these steps:
- Check cold. Measure when the car has been parked a couple of hours, or driven less than a mile. Tyres heat up as you drive and read higher when hot.
- Use a reliable gauge. Forecourt machines are convenient; a decent home gauge is handy for monthly checks.
- Do all four — and the spare. A full-size spare needs the right pressure too, if you have one.
- Replace valve caps. They keep dirt and moisture out of the valve.
- Recheck after adjusting. Inflate, then read again to confirm.
Aim to check at least once a month and always before a long trip. Tyres lose air naturally, and cold weather drops pressures further — a tyre set in summer can be noticeably soft by midwinter.
Tyre pressure checklist
| Task | How often |
|---|---|
| Quick visual check for soft tyres | Weekly |
| Measure pressures with a gauge (cold) | Monthly |
| Adjust for a heavy load or towing | Before each loaded trip |
| Check before a long journey | Every time |
| Inspect tread and condition | Monthly |
Tyres are one part of the bigger fuel picture
Correct pressures are an easy, free win — but they work best alongside other sensible habits. Smooth driving, removing unnecessary weight and roof bars, and keeping to sensible speeds all stack up.
The biggest saving of all, though, is simply paying less per litre. To see the difference good habits make to your real running costs:
- Work out your annual spend with the fuel cost calculator.
- Track each fill-up and your true mpg in your garage so you can spot the effect of keeping your tyres right.
- Heading somewhere new? Compare two areas to find the cheaper place to refuel.
The bottom line
Soft tyres cost you fuel, money and safety. A two-minute monthly check keeps your mpg where it should be and your tyres lasting longer — all for free.
Once your tyres are sorted, do the other easy thing too: find the cheapest fuel near you and check today's live prices before you fill up.
Frequently Asked Questions
Do underinflated tyres affect fuel economy?
Yes. Underinflated tyres increase rolling resistance, which makes the engine work harder and burns more fuel. Even a small drop in pressure can cost you a few percent in mpg.
What is the correct tyre pressure for my car?
Use the figures on the sticker inside the driver's door pillar or fuel flap, or in your handbook. Many cars list a higher pressure for heavy loads and motorway driving.
How often should I check tyre pressure?
At least once a month and before any long trip. Tyres naturally lose a little air over time, and pressures also change with temperature.
Should I check tyre pressure when tyres are hot or cold?
Always check when the tyres are cold, ideally after the car has been parked for a couple of hours or driven less than a mile. Hot tyres read artificially high.
Can overinflated tyres save fuel?
Slightly overinflating can marginally reduce rolling resistance, but it worsens grip, ride and tyre wear. Stick to the manufacturer's recommended pressures.