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Kenneth Rozmiarek
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Fuel mileage vs. inflation pressure?

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Kevin crows about super high tire inflation pressures increasing fuel mileage. What are the numbers? I run 50% empty miles with spring ride trailers and I can immediately tell the ride is much harsher @105 psi instead of the 85 psi I have used for 25 years. I pull 2 or 3 different trailers every day and can't measure any differences in fuel economy with accuracy. It seems the fuel mileage difference is much smaller than the ride difference.

Edited by: Kenneth Rozmiarek ( )

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Your
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Same theory if your riding a bicycle and you lower the pressure in the tires it becomes harder to petal because there is more surface making contact with the ground so if you air the tire up tight it's easier to petal due to the fact there is less surface making contact. Same theory on truck tires if they are aired up to the maximum they roll freer thus better fuel mileage. If the ride is more important lower your pressures to 85 and wear your tires faster.....

I'm only getting 350-400k out of trailer tires with minimal rotating. Drive tires, BFG ST230s, go 190- 260k. Tire wear is excellent!

Kenneth Rozmiarek,

I would boost the pressures and just see if those numbers go up too. I generally get 300 plus out of my drives running at 125-130psi

Your,

That is a lot higher pressure than I thought. You would be good for 50,000# on tandems! 75psi is recommended, but seemed low to me. Is it good for .1mpg or .2 mpg? 105 psi gives me a non- measurable inconsistent mpg number. ( ie. 0)

Kenneth Rozmiarek,

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Mel Help
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I agree with blackwood it does change the footprint weather it changes MPG if any is very little. But tires are designed for a certain footprint on the ground and when you change that footprint either by over inflation or under inflation your going to have irregular tire wear plus when you change that footprint you run a higher risk of hydra-plane. You would be better off using the mfg air pressure guide for the weight you carry on the axle

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Tire wear increases 20% for under inflated tires but only 5% for over inflated tires. Higher pressures reduce the flex in the sidewall which reduces heat too. In hot weather you should keep your tire pressures high. Conversely, cool weather lowers the air pressure which could cause heat and a blowout, so in cool weather you should keep your pressure high. Moral of the story, higher pressures are always better for your tires. Better fuel economy is a side effect.

Any numbers put out by the manufacturers are minimum recommended pressures. That includes what's on the sidewall of the tire.

This info was provided by Mike Beckett of MD alignment at the 2013 CMC. Mike works with tire manufacturers and engineers directly to diagnose tire wear issues. He is an expert in the field.

the psi stated on the sidewall is max recommended pressure for the tire. i do agree with the first paragraph though. one thing to think of is in rain, snow or on ice deflating the tires provides much better grip. i run my tires hard in the summer but softer in the winter.

Jerzy Zaleski,

Also that pressure on the sidewall is for max weight that the is design to carry

Mel Help,

Actually, that's not correct. Any time you see a recommended inflation pressure, it is the minimum. The max weight rating has the "max" pressure for that rating. A 14ply "G" rated tire has a "max" weight rating of 6175 lbs at 110 psi. However, it requires a Minimum of 110 psi for that tire to do its job properly. It is a common misconception of that being a maximum air pressure. It takes over 400 psi to cause a tire/wheel assembly to fail. The tire can even handle that much pressure. Usually the wheel fails or the tire is blown off the bead.

Your,

You can't over inflate a tire. The only time you should ever have to lower tire pressures is if you are getting uneven wear. I run all of my tires, steers, drives, and trailer at 125 psi.and get great life out of them. I would run higher pressures but I use the air line from the truck to inflate them and I prefer not to adjust that any higher.

Your,

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