Your take on tire pressure? (For fuel economy)

[nternal1]

Unbelievable! Is NOTHING ever simple?
The tires that came with my car say the max pressure is 44 PSI. The sticker on the door says 39 PSI and, though I don't have mine handy, I understand the manual says 35 PSI. What gives? I'm looking for good fuel economy (without distorting the results with tires that are over expanded) and my instinct is to go with 40 PSI. Any thoughts?

[R01k]

My door sticker says 35 psi.

[ahintofpepperjack]

The sticker on the door is the recommended pressure for the vehicle. The max pressure on the tire is the maximum pressure that the tire is rated for, Not the recommended pressure for your vehicle. The max pressure listed on the tire will vary depending on the model of the tire.

[nternal1]

The sticker on the door is the recommended pressure for the vehicle. The max pressure on the tire is the maximum pressure that the tire is rated for, Not the recommended pressure for your vehicle. The max pressure listed on the tire will vary depending on the model of the tire.

So why wouldn't one go with the max pressure listed on tire? Isn't higher pressure generally better for mileage?

[ahintofpepperjack]

So why wouldn't one go with the max pressure listed on tire? Isn't higher pressure generally better for mileage?

You can if your only desire is better MPG's.

The recommended tire pressure is based upon ride quality, proper tire wear, and safety.

[25Plus]

The German manual (Bridgestone Ecopia tires 165/65 R14) says 2.7 bar (39 psi) is the recommended tire pressure. When I got my Space Star, the tire pressure was 2.9 bar (42 psi) and I let it that high to save fuel. You should not use a tire pressure that is over the maximum allowed by the tire manufacturer, the Bridgestone Ecopia tires have a maximum of 3.0 bar (43.5 psi).

[foama]

The German manual (Bridgestone Ecopia tires 165/65 R14) says 2.7 bar (39 psi) is the recommended tire pressure. When I got my Space Star, the tire pressure was 2.9 bar (42 psi) and I let it that high to save fuel. You should not use a tire pressure that is over the maximum allowed by the tire manufacturer, the Bridgestone Ecopia tires have a maximum of 3.0 bar (43.5 psi).

I do a lot of long distance driving thoughout Europe. With the Bridgestone Ecopia summer tyres, the pressure is 3.0 bar front and back.
The pressure sticker says: 2.7 bar normal, 2.9 bar highway.
At 2.7 the front tyres become hand warm after an hour on the autobahn, at 3.0 it is much less.

[Cani Lupine]

Mine are at 50 PSI. At lower pressures, the sidewall flexes more, which heats up the tire more. That's why for high-speed driving and handling, you want more pressure. Lower pressure is only good for comfort, that's it. If the pressure is too low, the sidewall will pinch between the road and wheel when you hit a pothole and can damage the tire, leading to bubbles or a blow out.

Also, if you look on the sidewalls, notice how the warnings on tires say "danger from underinflation/overloading."

[MetroMPG]

Food for thought -- effect of tire pressure on rolling resistance:



From Snapshot: effect of tire pressure on rolling resistance

Also:



From: Experiment: coast down distances (rolling resistance) @ various tire pressures

Warning: excessive tire pressure may cause premature tire wear and/or adversely affect traction/vehicle handling.

[nternal1]

If I inflate my tires to the max (44 PSI) is that going to change the diameter enough to throw off my odometer and MPG indicator?