Higher PSI on tires equals 10% better MPG

[Carnivore]

Ok its not scientific but i have a 28 mile drive to work every day and with 14k miles on it, the best i ever EVER get is around 42mpg and that is with NO heat and NO AC on. Its mostly highway (up to 75 - 80 mph) with some tolls so there is some slowing down and then quick acceleration. I jacked my psi on my tires up to 40 psi yesterday and today I made my normal drive. I was actually stunned to see that I got 46.8 mpg on the same exact route with near identical conditions. :happy feet:

Edited May 20, 2010 by Carnivore

[jeff_h]

I jacked my psi on my tires up to 40 psi yesterday and today I made my normal drive. I was actually stunned to see that I got 46.8 mpg on the same exact route with near identical conditions. :happy feet:

 

I normally keep mine at 40 psi all around, as I have a 54 mile trip each way... I get better MPG than 32-34 psi but I don't know if it's 10% better, I would say maybe 5% better (over 33k miles I've averaged 39.2 MPG, will inch up a little now that warmer weather is back). In your experiment I wonder if the weather may have also been a player too?

[lolder]

The temperature gradient for mileage is about +0.2 mpg per degree F increase.

[Rodeo]

That's nothing!~

 

I just took a 1000 mile trip in a brand new spanking Milan with the 3.0 V6 in it and averaged 27.6 MPG with the stereo blasting and the a/c running full time. Not too shabby considering I had all the power I needed and I'm not a light-foot by no means. Just wait till that motor actually gets broken in!!

 

[William Horton]

I normally keep mine at 40 psi all around, as I have a 54 mile trip each way... I get better MPG than 32-34 psi but I don't know if it's 10% better, I would say maybe 5% better (over 33k miles I've averaged 39.2 MPG, will inch up a little now that warmer weather is back). In your experiment I wonder if the weather may have also been a player too?

I am a little uneasy pressuring to 40 psi for a couple of reasons, 1 - harsher ride and 2 increased hydroplaning possibility. I have driven two hybrids #1 Toyota Camry Hybrid with 36PSI in the tires for 60,000 miles with a lifetime avg of 36 MPG and now 4000 miles on the FFH with tires at normal pressures (not changed from FORD service) and still averaging 38-39 mpg on my daily 25mile each way trip with combined city/hwy driving.. In my experience, the 36 PSI is not harsh riding or decreases mileage enough to warrant any benefit of pressure over 36 PSI.. Of course, that's just my opinion, I could be wrong.. to quote Dennis Miller...

[pippin65]

with the outrageous prices of these tires, I think I'll keep them at the recommended psi...

[jeff_h]

with the outrageous prices of these tires, I think I'll keep them at the recommended psi...

 

That was another reason I went to 40psi, to get a more even wear instead of more on the outer edges when down at 32-33 or so.

 

I drove a Prius for over 120,000 miles at 40psi and the FFH for 36k thus far and after sampling with 32, 36, and 40, I'm satisfied with the 40.

 

Of course YMMV, each should drive whatever pressure works best for his/her situation.

[Bigkart]

Increasing tire pressure DECREASES its tendency to hydroplane because it has a smaller footprint: the weight is spread over a smaller contact patch. It also tends to round-out the contact patch, which will evacuate the water better. We increase pressures when racing in rain conditions for those very reasons.

 

Bob

[JimFFH]

I just increased to 38psi, waiting to see what happens over a tankful. I was reading a 2006 hypermiling article from Wayne Gerdes (helped pilot the 81mpg Fusion hybrid in DC) and he made a statement about setting psi up to 25% over the sidewall posted pressure. I'm guessing that is what he did to get that ridiculous 81mpg figure. 25% over 44 psi would be 55psi.

[akirby]

I just increased to 38psi, waiting to see what happens over a tankful. I was reading a 2006 hypermiling article from Wayne Gerdes (helped pilot the 81mpg Fusion hybrid in DC) and he made a statement about setting psi up to 25% over the sidewall posted pressure. I'm guessing that is what he did to get that ridiculous 81mpg figure. 25% over 44 psi would be 55psi.

 

NO NO NO! Do not exceed the tire pressure on the sidewall of the tire under any circumstances. That's the maximum safe pressure. Going over it is risky regardless of what the hypermilers tell you. Would you believe Wayne or Michelin, Goodyear, etc.?

[JimFFH]

NO NO NO! Do not exceed the tire pressure on the sidewall of the tire under any circumstances. That's the maximum safe pressure. Going over it is risky regardless of what the hypermilers tell you. Would you believe Wayne or Michelin, Goodyear, etc.?

 

I definitely won't go above 44. Read this on the Insight forum separately from the Gerdes article. It makes total sense.

 

"You are safe to fill the tires to the max inflation pressure on the sidewall when COLD, the fact that they warm up while driving is factored in and there is even more of a fudge factor too, the tires are underrated to account for pretty much every condition including a few patches, some damage, and terrible roads. Many people in the 1st Gen forums run higher than the sidewall max and I haven't seen any issues come of it, but do so at your own accord. The fuel savings of running above what Honda suggests is significant, especially with the front of the car where it is heavier. "

 

http://www.insightcentral.net/forums/honda-insight-mpg/17486-tire-psi-mileage.html

[JimFFH]

With 40 psi, I was getting 46mpg down to a quarter tank, that is until the wife got a hold of it and dropped it down into the 44s. That is with no AC running, mainly driving 23miles to work, mostly 55-65 mph highway speeds.