Fuel economy and tire care

Explanation

Fuel economy. Fuel use rises steadily above 45 mph; cars and light trucks use about 50% more fuel at 75 mph than at 55 mph. To save fuel: drive sensibly and obey the speed limit, avoid rapid acceleration and sudden stops, don’t haul cargo on the roof, remove excess weight, keep the engine maintained and tires properly inflated, use the recommended motor oil, and combine trips — several short trips from a cold start can use twice as much fuel as one longer trip.

Tire pressure. Tires can lose up to 1 psi a month, so check all of them, including the spare, once a month or before a long trip. Check them cold (before driving or at least three hours after). Compare your gauge reading to the sticker inside the driver’s door jamb or the owner’s manual — not the number on the tire sidewall.

Tread depth. Check tires for wear monthly or before a long trip. Penny test: put Lincoln’s head into the shallowest groove. If any part of his head is covered, the tread is legal and safe. Below about 1/16 inch, grip in bad conditions is greatly reduced.

Example

Before a road trip you check the tires first thing in the morning. The door sticker says 35 psi; one tire reads 31. You add air until it reads 35, ignoring the different number printed on the tire sidewall.

Common mistake

Filling tires to the number on the sidewall. That is not the recommended pressure for your vehicle — use the door-jamb sticker or owner’s manual.

What the manual says

Fuel consumption increases steadily above 45 miles per hour, with passenger cars and light trucks using approximately 50 percent more fuel traveling at 75 miles per hour than at 55 miles per hour.

Tires have been known to lose up to 1 pound per square inch (psi) every month, so check all tires, including your spare, once a month or before a long trip.

If any part of Lincoln’s head is covered by the tread, you’re driving with the legal and safe amount of tread.