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Old 04-04-2014, 08:51 PM   #1
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Increased my MPGs

Just a quick note I wanted to share. I increased my Hancock Dynapros MT 315-70r-17 from 33psi to 40psi (Did it because my tires began to look smaller by the day) Had this ever happened to you? anyways the point is my MPG went from 14s- low 15s to 16.5 average within a day... Ride difference is not that significant. Just saying...


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Old 04-05-2014, 01:57 AM   #2
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Originally Posted by Criossk View Post
Just a quick note I wanted to share. I increased my Hancock Dynapros MT 315-70r-17 from 33psi to 40psi (Did it because my tires began to look smaller by the day) Had this ever happened to you? anyways the point is my MPG went from 14s- low 15s to 16.5 average within a day... Ride difference is not that significant. Just saying...

You might want to chalk test your tires. Even at 33 psi you are probably only wearing the center of the tread. Any money you save on gas will be used to prematurely replace tires.

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Old 04-05-2014, 04:32 AM   #3
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It happens to me every day because I keep my tires at manufacturer recommended tire pressure of 43 PSI. I have also measured the gain to be almost 1 MPG compared to 30 PSI. My KM2s do feel slightly like riding on knobbiest but I got used to after a couple of weeks. The It also improves the how the acceleration feels.

The infamous chalk test just optimizes footprint but does not take into account tire loading which is much different high the load rating tires or fuel economy. The max tire pressure on my KM2s is 80 psi so going from 28-30 psi which the chalk test indicates to 43 psi surprisingly doesn't change the footprint that much. i always do a 5 tire rotation every 5k miles.

I chalk test like 15" wheels, CAIs and other old habits are hard to die.
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Old 04-05-2014, 09:57 AM   #4
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This totally depends on the tire you run. Running even 33psi in a 10ply load range E M/T tires on bumpy back roads will certainly cause undo stress and ware on suspension parts as well as premature tire wear. Max inflation is determined by vehicle weight and load i.e. A diesel pickup will require 40psi to maintain the same ride and tire wear as a Jeep at 27psi with the same tire.

Running higher pressure in a C rated highway tire is another story. Tire wear is not as critical.

Bottom line ... If you are that worried about mpg put your Jeep back on 29" road tires, run at factory determined psi and keep it at stock height. If you want the best possible ride and the most mileage from your big tires run lower pressure.
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