Don’t Over-Inflate Tires; Stick With Car Maker’s Original Pressure Recommendation

Question: I recently purchased tires for my Toyota Corona and noticed that the new tires have a maximum pressure rating of 44 pounds per square inch, while my old tires were rated at 35 psi. To me, this would mean I should use a higher pressure in the new tires. I tried this out and the tires seem to run cooler after a long drive. What’s your advice?

--E.B.

Answer: Unfortunately, your logic is off track. Tire manufacturers and auto makers always recommend that you stick with the originally recommended pressure for a vehicle’s tires, which usually is imprinted on the passenger-side doorjamb or in the glove compartment.

Tire air pressure is a greatly misunderstood subject among motorists. An estimated 250,000 accidents occur every year because of under-inflated tires, according to the National Highway Traffic Safety Administration.

What you are proposing is to run your tires over-inflated. Toyota originally recommended 28 psi for your car, according to Goodyear Tire experts. It was a decision based on the car’s handling, comfort, braking, fuel efficiency and tire life.

Over-inflating the tires will change all that, possibly increasing your fuel efficiency but also reducing the effectiveness of your brakes in a panic stop and reducing the car’s ability to hold the pavement in a hard turn.

It is true that an over-inflated tire runs cooler, but that shouldn’t count for much. In fact, the tire may wear out more quickly at a higher pressure than at the standard pressure.

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Why is the maximum recommended pressure of new tires creeping up? Tire makers are responding to the automobile manufacturers who want tires with lower rolling resistance to improve fuel efficiency. Also, auto makers are designing cars to ride lower to the ground and with smaller wheel wells, which require tires with a squat shape. These tires, known as low aspect ratio tires, run at higher pressures.

But none of that means these tires should be inflated to maximum capacity. Indeed, nobody wants to recommend that motorists experiment with recommended tire pressures for obvious safety and liability reasons.

In any case, you should remember to check the pressure frequently, particularly as the seasons change. For every 10-degree drop in outside air temperature, the air pressure inside the tire drops 1 psi.

* Vartabedian cannot answer mail personally but will attempt to respond in this column to automotive questions of general interest. Do not telephone. Write to Your Wheels, 1875 I St. N.W. #1100, Washington, D.C. 20006 or e-mail to Ralph. Vartabedian@latimes.com.