Quick answer
Yes, underinflated tires create more rolling resistance, forcing the engine to work harder and use more fuel. Keeping tire pressure at recommended levels can improve mpg.
Detailed answer
Driving on underinflated tires is a hidden factor that reduces fuel economy, as the engine must overcome increased friction between tire and road. Rolling resistance spikes when tire pressure dips below the recommended psi, causing your car to burn more fuel to maintain speed. The difference might seem small at first, but over time or in long drives, it adds up to noticeable extra costs.
How does it work? Properly inflated tires maintain an optimal contact patch with the road. When pressure drops, the tire flattens out more, increasing the area in contact with the pavement. This effect eats into momentum. You’ll find that accelerating, and even cruising, requires more engine power. It’s akin to pedaling a bike with partially flat tires—each push feels heavier.
This scenario also affects handling and safety. Underinflated tires can overheat, leading to blowouts, particularly on highways. They also wear unevenly, forcing you to replace them sooner. That’s another indirect cost. Checking your tire pressure monthly or before a significant trip is a straightforward habit. Most cars have a sticker on the driver’s doorjamb or in the owner’s manual indicating the recommended psi—often ranging from about 30 to 35 psi for passenger vehicles, though it varies by model.
If you haul extra weight, tire pressure might need slight adjustment. Seasonal temperature changes can also alter psi. For every 10-degree Fahrenheit drop in ambient temperature, tires can lose around 1 psi. Conversely, warm days can inflate them more. A quick gauge reading ensures you’re not inadvertently losing mpg on your commute or road trip.
Additionally, many modern cars come with Tire Pressure Monitoring Systems (TPMS). However, the system might only alert you when pressure is significantly low—well below the recommended level—so a manual check still proves beneficial. Some drivers might run tires slightly above factory specs for lighter loads to reduce rolling resistance, but consult your manual or a tire professional to avoid compromising ride comfort or traction.
In short, underinflated tires can subtly sap your fuel budget. By maintaining proper inflation, you not only improve mpg but also enhance safety, tire longevity, and handling. It’s one of the simplest, most effective car care steps you can take—no specialized mechanical skills needed, just a reliable gauge and a few minutes to check each tire. Do it regularly, and you’ll likely see fewer fill-ups and a smoother drive.
