Your Tires Are Part of Your Fuel Budget

Tires rarely get invited into conversations about fuel budgets. They should.

A tire flexes as it rolls. When pressure is too low, that deformation increases and the vehicle has to overcome additional rolling resistance. The engine supplies the extra energy, which means the effect eventually appears at the fuel pump.

The correct PSI is on the vehicle, not the tire

The large pressure number molded into a tire's sidewall is commonly misunderstood. It is not automatically the pressure the vehicle manufacturer wants you to use for normal driving.

Look instead for the vehicle's recommended cold tire pressures, commonly printed on the placard inside the driver's door area and listed in the owner's manual.

Why “cold” matters

Tire pressure changes with temperature. Driving also warms the tire, which changes the reading. That is why manufacturers generally specify cold pressure.

Seasonal temperature changes can be enough to make a previously acceptable tire noticeably low. A warning that appears during the first major cold spell may be related to temperature, but it is still a reason to measure the tires rather than simply dismiss the warning.

More pressure is not the goal

If low pressure creates extra resistance, deliberately overinflating might sound like an efficiency shortcut. It isn't the right target.

The goal is the manufacturer's specification. Tire pressure also affects handling, tire wear, load capacity and the size and behavior of the contact patch. Fuel economy is only one part of the tire's job.

Make the check routine

A basic pressure gauge can live in a glove box. Checking periodically — and particularly around large seasonal temperature swings or before a long trip — turns an invisible variable into something manageable.

The payoff is not a spectacular one-time MPG jump. It is avoiding an efficiency loss that otherwise follows the car mile after mile.