P Tires and MPG

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[quote author=landtoy80 link=board=2;threadid=12909;start=msg120143#msg120143 date=1079123656]

Does it mater what the max pressure is? If max is 35 then it is too high but what about 85psi max?
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You are right, you can use up to the max pressure of the tire, which in turn will give you the max load carrying capacity the tire is rated for, but you don't have to, if you are not carrying all that load.
My BFG's are rated for 3305 pounds @ 65psi cold, that means I have to use 65 psi if the gross weight of the truck was 13,220 pounds ( 3305x4).
If you are not carrying the max load , you don't have to use the max pressure. But you can if you want, the only thing that will happen is that you will be bouncing around all over the place.
reducing the pressure will give you a more comfortable ride without any safety concerns, however, I have not been able to find a chart that relates Tire pressure to load capacity at different levels and for most tires the best starting point is what the owners manual calls for pressure wise. :cheers:
 
THe owners mamual tire pressure PSI would only be for stock tires.
You go to a LT with 85 max and the stock tire was a P tire with 35 max and 28 is what the manual says. You will be underinflated at 28 with a 85 max tire.
 
mtycruiser, hey maybe the warmer air helped or something.? Hey I don't really care, I just know it improved. You will notice I said this is only with two tanks. Who know maybe I've had a tail wind?
 
Each week I drive 320 (freeway) miles to work and 320 miles back. I get 17 MPG all the time with my 3" lift J springs and BFG 315 X 75 16 tires. I always run them on the street at 45 to 50 psi. I get a total of 374 miles on the 22 gallon tank. After my drive home I am able to get a few days driving around town on the tank before I gas up for the return trip. I use a GPS to get actual mileage driven for mileage calculations. I drive 60 - 65mph most of the time. I think slow thoughtful driving and high tire pressure helps with mileage.
 
[quote author=landtoy80 link=board=2;threadid=12909;start=msg120709#msg120709 date=1079214590]
Did you regear the diffs?
I got 16 with P270 tires and went to 13 with LT285 and the ARB front bumper.
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Yes, I switched to 4.88 gears. I also drive just about the whole way at sea level, I bet the milage would go down a bit at a higher altitude.
 
I aired up to 60psi and got 14mpg with a VERY strong head wind.
THe down fall was when it was raining. A couple of times when stopping at a stoplight, the ABS would activate just before the vehicle stopped. I will air down to about 55psi and see if I get more tire on the road.
 
[quote author=Chris Geiger link=board=2;threadid=12909;start=msg120781#msg120781 date=1079227845]
Yes, I switched to 4.88 gears. I also drive just about the whole way at sea level, I bet the milage would go down a bit at a higher altitude.
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Actually you get higher gas mileage at higher altitudes. Less air, less fuel/air mix, more mpg....less power.

i'm surprised you are getting that kind of mileage with 35" tires and 4.88 gears.

Kumar
 
[quote author=inacoma link=board=2;threadid=12909;start=msg121327#msg121327 date=1079327897]
Actually you get higher gas mileage at higher altitudes. Less air, less fuel/air mix, more mpg....less power.

i'm surprised you are getting that kind of mileage with 35" tires and 4.88 gears.

Kumar

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I just made the long drive to work again today and got 17.3mpg but I had a tail wind this time. I run 50psi in the tires and drive like a little old lady.
 
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