Assuming load range E tires that are 65-70 (front/rear) on the highway.
What are you running on:
Hard packed, but bumpy dirt with some occasional rocky patches
Sand
Super soft sand
[Edited on 12-21-2017 by JZ]aguachico - 12-17-2017 at 07:45 PM
In the process of dialing this in. most of the weight is on the front when not loaded. Going to the scales to confirm the weights and using this
chart.
The only reason to air down is to smooth out the ride on rough roads or to get out of the sand. I run 35 psi in my Tacoma with 32 inch tires loaded
and 45 psi in my GMC Z71 (1/2 ton) with 33 inch tires. When in the sand I drop both to 25 psi. If the sand is real soft then 15-20 psi. I have went as
low as 10 psi to get out of a very soft sandy beach one time. Some of it depends on how hard the sidewall is. The BFG TA KO tire has a hard sidewall.
If you have a soft sidewall I would be very careful on how low I would go. I went as low a 4 psi in a class 8 race truck with BFG race tires. He had a
broken axle so it was only one wheel drive and he made it thru some very soft sandy sections near San Felipe.
When the tire pressure is real low say 15 or less you have to be very careful not to make hard turns with the steering wheel or you could pop the
bead. basautter - 12-18-2017 at 05:13 AM
Mid 20s on gravel, around 20 is soft sand. Works for me, although probably not the best for tire life. Doug/Vamonos - 12-18-2017 at 06:58 AM
On my f-250 diesel I run 285x75x18 Nitto Mud Grapplers. On badly rutted roads I go down to 20. Sometimes less. Adjust speed accordingly. I haven't had
a flat tire on my trucks in years and tire wear is fine. If I were stuck I'd drop it down even more till I get a good contact with the tread.PaulW - 12-18-2017 at 07:44 AM
As Mentioned
Go to the scales with load and no load. Then go to the tire spec for load vs pressure. You will probably have to call the engineer at the tire
company?
Set your pressure about 5 psi above what the load/psi chart says. The result is optimum tire wear and the softest ride as is possible.
I found my front pressure load does not change vs the rear load.
When doing the above and driving on bad washboard roads your pressure will be to high for comfort, however lower pressure is not bad provided you
keep your speed down. Pumping back up for the paved highway is required to get back to the proper psi (See above). Now days airing back up is less of
an issue with modern electric inflate devices.
Do I air down on my F350, Never, I just slow down. To much of a hassle to air up. With my Jeep I just keep the pressure at 14 psi and drive very slow
when I have to use pavement. Yup its a dedicated off roader.bkbend - 12-18-2017 at 09:27 AM
Once I did the scales/charts/guesswork to find my highway pressure for a 1 ton PU with E rated tires I decrease by 1/3 for bumpy gravel/rock, 1/2 for
sand, and 2/3 escaping soft sand. I don't do much sand driving because it takes too long fill big tires up to higher E tire pressures.David K - 12-18-2017 at 10:01 AM
Once I did the scales/charts/guesswork to find my highway pressure for a 1 ton PU with E rated tires I decrease by 1/3 for bumpy gravel/rock, 1/2 for
sand, and 2/3 escaping soft sand. I don't do much sand driving because it takes too long fill big tires up to higher E tire pressures.
This JZ - 12-18-2017 at 12:03 PM
If I go from 65 down to 35 in dirt it makes a world of difference in ride comfort. 25 gets through pretty deep sand.
[Edited on 12-18-2017 by JZ]aguachico - 12-18-2017 at 12:35 PM
6.0 ford. 295/75 - r16 KO2's.
washboard down to 30#
Don't do much sand.Tioloco - 12-18-2017 at 05:13 PM
My F250 6.7 diesel with 35x12.50-17 BFG A/T on 17x9
8,200 lbs total weight
30 psi hardpack dirt
20 psi sand
15 psi really soft sand (driving carefully to not roll tire off bead)
I carry onboard air to make adjustments as neededJZ - 12-19-2017 at 06:19 AM
My F250 6.7 diesel with 35x12.50-17 BFG A/T on 17x9
8,200 lbs total weight
30 psi hardpack dirt
20 psi sand
15 psi really soft sand (driving carefully to not roll tire off bead)
I carry onboard air to make adjustments as needed
[Edited on 12-19-2017 by JZ]Tioloco - 12-19-2017 at 10:56 AM
JZ- I run mine at 48 psi on highway.
Sidewall max states 65psi
3,195lbs max
10 ply
Load Range E
[Edited on 12-19-2017 by Tioloco]Doug/Vamonos - 12-21-2017 at 06:56 AM
I always run my tires at 60 psi on the highway. 2005 F250 crewcab 6.0. Weighs about 8,000lbs. Nitto Mud Grapplers (excellent tires for me), 285x75x18.
Yes, airing them down requires a LOT of time on the compressor to air them back up! Only do it when I really need to.PaulW - 12-21-2017 at 09:30 AM
My F350 weighs 8000 and my front pressure is 50 and rear is 40 unloaded 60 with my typical load. Pressures are per manufactures load vs psi chart.
Good wear all the way to bare and reasonable ride.aguachico - 12-21-2017 at 08:05 PM
My F350 weighs 8000 and my front pressure is 50 and rear is 40 unloaded 60 with my typical load. Pressures are per manufactures load vs psi chart.
Good wear all the way to bare and reasonable ride.
that's what I'm talking about. Unloaded, 2/3's of the weight is on the front axle.
