Tyre pressure, rolling resistance and fuel use

Rolling resistance falls as pressure rises, up to a point. A 0.4 bar-low tyre costs fuel (and EV range) you can measure on a long trip. Makers already chose a number that balances wear, wet grip, ride and consumption.

Running 5 psi over the placard to chase mpg is an old myth. You might see a fraction of a mile per gallon. You will see centre wear and a worse ride.

The high-value habit is not over-inflation. It is not being low. A monthly check keeps you at the engineered number.

Low-rolling-resistance OEM tyres on hybrids and EVs are designed around the placard. Substituting a softer aftermarket tyre and then dropping bar undoes both the compound and the pressure.

Alignment and worn dampers also cost fuel. Pressure will not fix a car that is toeing out.