Correcting underinflated tires recovers fuel economy you were already losing, it does not create extra efficiency beyond that. fueleconomy.gov, the site the US Department of Energy and EPA run jointly, states proper inflation improves gas mileage by 0.6% on average, up to 3% in some cases, while every 1 psi of underinflation costs about 0.2%. The effect is real, modest, and larger on EVs. Never guess the number: use your door jamb placard.
Underinflated tires: correcting a loss, not creating a gain
The fuel economy claim attached to tire pressure is really two claims wearing one headline, and only one of them is well supported. The first is that underinflated tires waste fuel, which is documented and straightforward: a tire running low deforms more as it rolls, which increases rolling resistance and asks the engine or motor for more energy to cover the same distance. Correcting that underinflation lets the tire roll the way it was designed to, and you get back mileage you were already losing.
The second, implied claim is different: that pushing pressure higher than the placard number recovers even more fuel on top of that. That is not what the cited research below supports. Correcting underinflation returns efficiency a tire was designed to have. It does not create new efficiency by going further. That distinction changes what a driver should actually do: check pressure on a schedule against the number the vehicle specifies, not chase a higher number hoping for a bigger saving.
What fueleconomy.gov actually states, and since when
fueleconomy.gov is the most direct authority on this question, since it is run jointly by the US Department of Energy and the Environmental Protection Agency. As of 2026 the site states that keeping tires inflated to the proper pressure improves gas mileage by 0.6% on average, up to 3% in some cases, and that underinflated tires lower gas mileage by about 0.2% for every 1 psi drop in the average pressure across all four tires. The agencies have carried a version of this guidance since at least 2017 (DOE Fact #983, published June 26, 2017), and it remains current on the site's maintenance page today.
Those are the real numbers: a modest, single-digit percentage, not the dramatic claims some articles imply. fueleconomy.gov separately notes that a 5 to 7% reduction in a tire's inherent rolling resistance, a tire design factor rather than something inflation alone achieves, raises fuel efficiency by roughly 1%. That figure is a useful sense of scale for how much any one factor here realistically moves the needle.
Overinflating past the placard: not the hack it looks like
If 0.6% is available from proper inflation, it is tempting to reason that a few extra psi past the placard number buys a few tenths more. The cited research above does not support that trade, and the reasons against it are mechanical, not statistical. Overinflating shrinks a tire's contact patch, the area of rubber actually touching the road, which reduces wet-weather grip and stopping traction. It also concentrates wear on the center of the tread rather than spreading it evenly across the tire, shortening the tire's useful life, a cost that outweighs any speculative fuel saving.
The pressure figure on your door jamb placard already reflects the engineer's balance of ride, grip, tread wear and efficiency for that specific vehicle and tire combination. Going past it trades measurable safety and tread life for a fuel effect that no named source in this article supports. See our guide to what PSI your tires should actually be for why that number, not the sidewall's maximum figure, is the one that matters.
Why EVs feel it more: rolling resistance and the energy budget
The efficiency effect of tire pressure is not identical between a gasoline car and an EV, and the difference comes down to where the energy goes. fueleconomy.gov's own "Where the Energy Goes" breakdown for gasoline vehicles shows that on the highway, a typical engine delivers only about 22 to 30% of its fuel energy to the wheels, the rest is lost to engine heat and friction before it ever reaches the tire. Its equivalent breakdown for EVs shows roughly 71 to 73% of battery energy reaching the wheels on the highway, before regenerative braking is even counted.
Because so much more of an EV's stored energy actually reaches the tire, rolling resistance at that tire claims a proportionally larger share of the total energy budget than it does in a gas car, so a change in tire pressure has more of the budget to work against. A study by Geely's research institute, tire maker Linglong and ExxonMobil, reported through SAE's Mobility Engineering Technology, modeled this directly: against a 360 km baseline EV range, tires with poor air retention measured out to roughly 344 km of real-world range versus about 353 km for tires that held pressure well, a gap of around 9 km, or roughly 2.5%, attributable to rolling resistance from gradual underinflation alone. The effect is real and worth minding on an EV. It is still not a reason to run pressure above the placard.
The real lever: check monthly, not chase a number
Every figure above assumes the tire was actually underinflated to begin with, and that is the part a driver controls. The biggest real-world lever is not a cleverer number, it is simply checking pressure on a schedule instead of never. Tires lose pressure gradually through normal permeation and faster with temperature swings, so a tire correct in spring can be several psi low by the time the weather turns. See why morning and evening readings disagree for why the timing of the check changes what the gauge shows.
The correct number for your vehicle is never on the tire's sidewall, it is on the door jamb placard, and a gauge that reads correctly matters as much as checking at all. Our guide to whether you still need a separate tire pressure gauge covers why a built-in inflator gauge is not always the last word, and confirming your inflator's gauge is telling you the truth is worth doing before you trust any single reading. A good portable inflator makes the monthly habit fast enough that skipping it stops being the easy option.
Quick reference: what is sourced here
| Claim | Named source | Figure |
|---|---|---|
| Underinflation lowers mileage | fueleconomy.gov (US DOE / EPA) | About 0.2% per 1 psi drop, average of all four tires |
| Proper inflation improves mileage | fueleconomy.gov (US DOE / EPA) | 0.6% average, up to 3% in some cases |
| Lower rolling resistance improves efficiency | fueleconomy.gov (US DOE / EPA) | 5 to 7% less rolling resistance yields about 1% better efficiency |
| EV range lost to poor tire air retention | Geely Research Institute, Linglong, ExxonMobil, via SAE Mobility Engineering Technology | About 9 km on a 360 km baseline, roughly 2.5% |
| Overinflating past the placard for economy | Not supported by any source above | No figure to cite; contact patch and wear trade-offs argue against it |
Read the table as it is meant: modest, sourced, and every number tied to a name you can go verify yourself.
FAQ
Does underinflated tire pressure really hurt gas mileage?
Yes, modestly. fueleconomy.gov states underinflated tires lower gas mileage by about 0.2% for every 1 psi drop in the average pressure across all four tires, a real but not dramatic effect.
How much fuel do I actually save by keeping tires properly inflated?
fueleconomy.gov puts the average improvement at 0.6%, up to 3% in some cases, when tires are kept at the correct pressure rather than left to drift low.
Should I inflate my tires above the recommended PSI for better mileage?
No. The door jamb placard reflects a balance of grip, tread wear, ride and efficiency for your specific vehicle. Overinflating shrinks the contact patch and wears the tread center faster, and no source cited here supports it as a mileage strategy.
Does tire pressure affect an EV's range more than a gas car's mileage?
The underlying mechanism, rolling resistance, is the same, but EVs deliver a much larger share of their stored energy to the wheels, so rolling resistance is a proportionally bigger factor in an EV's energy budget than in a gas engine's.
What is the correct tire pressure for my car?
It is not printed on the tire's sidewall. Check the placard inside the driver's door jamb or your owner's manual, and treat that number, not a generic figure, as the one that applies to your vehicle.
How often should I actually check my tire pressure?
Monthly, and before long trips, is the routine fueleconomy.gov and most tire makers point to. Checking cold, before the car has been driven, gives the most consistent reading.
Will a fancier or more expensive inflator save me more fuel?
No. The saving comes from correct pressure, not from the device used to reach it. A functional inflator with an accurate gauge and a monthly habit delivers the same result as any premium unit.