Tires lose about 1 PSI per month just sitting there, and another 1 PSI for every 10-degree drop in temperature. Most people only notice when a tire looks visibly low — by then you're already down 8-10 PSI and doing real damage.
How to check
- Find the recommended PSI on the driver's door jamb sticker (not the tire sidewall — that's the max rating)
- Check when tires are cold — before driving or at least 3 hours after
- Use a decent digital gauge (the pencil-style ones are garbage)
- Don't forget the spare
Why it matters
Under-inflated tires increase rolling resistance, which means worse fuel economy — roughly 1% for every 3 PSI low according to the DOE. They also wear the outer edges faster, meaning you'll replace them thousands of miles early. Over-inflated tires wear the center and reduce your contact patch, hurting grip.
Quick action
Grab a tire gauge right now, walk out to your car, and check all four tires. If you don't own a gauge, get a digital one for under $10 — it'll pay for itself in fuel savings within a month.
