Driving
Tyre pressure and fuel economy
Tyres are the only part of the car in contact with the road. If they are under-inflated, they flex more and create more rolling resistance. That can increase fuel use and wear.
Quick answer
Under-inflated tyres can raise fuel use because they increase rolling resistance. Check the pressure on the door placard when the tyres are cold, and use the vehicle manufacturer's figure.
Key takeaways
- Low pressure increases rolling resistance.
- Check pressure cold and use the door placard.
- Over-inflating is not a safe fuel-saving shortcut.
What rolling resistance means
A tyre deforms as it rolls. More flex means more energy lost as heat. Keeping the tyre at the recommended pressure reduces that flex without making the tyre too hard.
Pressure also affects grip, braking and wear. The goal is the recommended pressure, not the maximum printed on the sidewall.
How to check it
Check when the tyres are cold, before a long drive or after the car has been parked for a few hours. Use the placard in the driver's door jamb or fuel-filler flap, not the sidewall maximum.
Check all four tyres and the spare if you have one. A slow puncture can hide as a small monthly pressure loss.
The fuel-saving limit
Correct pressure helps, but it will not transform a thirsty car. Driving style, speed and route usually matter more. Do not over-inflate to chase a small saving; it can reduce grip and cause uneven wear.
- Check monthly and before long trips.
- Adjust for heavy loads if the placard gives a loaded pressure.
- Replace damaged valves or tyres that keep losing pressure.
Questions
Does low tyre pressure waste fuel?
Should I use the maximum pressure on the sidewall?
How often should I check tyre pressure?
Sources
- fueleconomy.gov — driving habits — Official US guidance on idling, speeding, loads and driving behaviour.
- fueleconomy.gov — factors that affect fuel economy — How speed, weather, load and maintenance can change consumption.
- fueleconomy.gov — US fuel-economy ratings — EPA label values, test-cycle context and consumer guidance.
Try the calculator
Related guides
Track real fuel economy: tank-to-tank
Measure your car's real MPG or L/100 km using odometer readings and fill-ups, and avoid the common errors that distort the result.
Does air conditioning use more fuel?
How car air conditioning affects fuel use, why speed changes the answer, and when open windows are the better choice.
What is the most fuel-efficient speed?
Why there is no universal magic speed, how aerodynamic drag changes the picture, and how to find an efficient pace for your car.
A note on prices and rules
Page last reviewed: . Formulas are covered by automated tests. Prices are inputs, not live data.