air pressure, dirt roads

[fifty]

Hey all. I am going to be running 37x12.5x20 nitto trail grapplers on my 350. Anyone play with tire pressures with them? I am trying to get a good starting point for fire roads etc...

There are a couple trails that are by my in laws that are about 15-20 miles into the hills that I would like to hit up...but I have a feeling the 60 psi I run on the street would not be ideal...

Suspension set up will be 4 wheel coil overs, not sure the spring rates yet, but probably 300 over 500 fronts and 250 over 400 rears. But maybe not...

[dazdillenger]

Are the roads full of washboard sections? If so, good luck. I doubt anything you do will smooth them out while still keeping the truck streetable. Maybe throw 500lbs in the back-lol.

[SmokeyAussie]

just depends on how rocky the gravel road its...what speeds you will be doing and what weight you have in teh back.

i run mine at 30psi and it helps soak up a lot of the small stuff, and there is less risk of you getting a tire staked or torn on sharp rocks

it will be something that is personal prefferance to how low a psi you go, i had three or four trials with different pressures to see what one i thought was best. you will be suprised as to how big of a difference 5psi makes.

[fifty]

Thanks for the info guys. The trails will be assorted...I am sure there will be wash board on parts, washed out on others

As for weight, I have an ARE shell on the back, plus two dogs (thats 125 lbs right there) and gear for me and the missus for a few days...That might total out to be around 400 lbs or so.

As for speeds. well, controllable speeds on the long relatively clear cut roads, (40 or so) much much slower as things get cut up rocky and in need of 4wd...

[351fifty]

Where are you stationed? And will you be able to air them back up when you get back on the beaten path when you return?

[SmokeyAussie]

Originally Posted by fifty

Thanks for the info guys. The trails will be assorted...I am sure there will be wash board on parts, washed out on others

As for weight, I have an ARE shell on the back, plus two dogs (thats 125 lbs right there) and gear for me and the missus for a few days...That might total out to be around 400 lbs or so.

As for speeds. well, controllable speeds on the long relatively clear cut roads, (40 or so) much much slower as things get cut up rocky and in need of 4wd...

one other thing i thought of as i went bush lastnight and run a tire off the rim...dont corner too aggressively or to tight with a bit too much speed especially with lower tire pressure your tire will run straight off and you will be doing this like i did.

all you would want is a little bagging in the side walls, enough to soak up some of the rocks and other crap on the track and you should be sweet!

[xjeeper]

I run 25psi in mine on sand, 30 in mixed offroad, more for traction than ride.

[Dan Lee]

You will notice an amazing difference, you will be fine at 20 psi running washboard roads. I didi a section that was really rough at street pressure in my other truck, drop it low to 20, stll handled great & absorbed so much of the bounce. An on board air compressor will be a good investment!