Airing down... To what pressure?

[LSUDenver]

I am running BFG 245/75/16 Mud Terrains on a DII. On a tire like this when you "air down" what are you guys airing down to?

In Colorado, I mainly run rocky loose stuff with incline. Some mud, but not a lot.

Thoughts for a new Rover enthusiast?

 

[gmookher]

I ran 21 rd today, its a 9 rated trail, I got thru 85% of it, had some go rounds and couldnt get thru the last 2 obstacles that rquire 35s
maxxis bighorn MT
i rode 15psi 265/75 16
hway i run 34psi
in snow about 11psi

for easier 8 and below trails, i'll try at 17psi or 18 if its a 7

 

[LSUDenver]

Gem,

Even though my tire says 80 psi, are you saying that I should run 34 psi normally no matter what?

 

[post]

I wouldn't run 80 psi even if that's the max psi...

 

[DiscoveryXD]

the tire says that as a max. do not run at 80psi!

the guys at a tire shop put my new MT's on and had the psi at 60. that made the truck feel like it was bouncing over speed bumps.

 

[rmuller]

80psi is the MAX you can put in before it gets dangerous.. I run mine 32front/38rear usually... at 80psi the truck will ride like a skateboard.

 

[gmookher]

yep,you'd have to be crazy to run 80 psi!!! it would be a jarring and hard bouncy ride not to mention un safe. 32 is a standard psi for radial tires on road.start there!

IIRC, each vehicle actually, per DOT has a tire psi rating recommended from the manufacturer, usually in the door jamb or glove box or somewhere obvious.
never bothered to see what the rover folks suggested since I am NOT running a stock tire

I suggest you try 30 psi up front and 32 in the back
then go up 2psi front and 2psi rear till you are at 38 front and 40 rear
30/32
32 all around
32/34
34/36
35 all around
36/38
38/40

its really alot about driving style and preference

run the same windy flat road, then find section with bumps, and then try evasive manuvers somewhere safe(make believe) and after running say

thats a max rating, no one runs that high a pressue that I know. some d2 owners run as high as 37-38psi, but I feel my rigg handles safer a few psi lower. if i am really loaded up, i will go up to 36psi rear but usually amd fine with 34 all around

then try the same offroad on your rockiest trail and then the sandiest trail and then the snowiset trail DRY, when wet I drop down an extra 3 psi
for snow and ice, if its over 6" off road i start at about 14psi and have been down to 10psi during winter romp

15 all around
18 all around
21 all around
for fire roads, 25 is fine
for green trails here in co rated 1-to 5 22 will work
for trails rated 5 to 7, run 18psi
for 8's run 15 to 17
for 9's run 12 to 15
I came to my prefered pressure via this route
remember the more you drop psi the lower the pumpkin sits!
just as a sideline, same applies to motorcycles,bikes, cars, etc

http://www.nhtsa.dot.gov/cars/rules/TireSafety/ridesonit/brochure.html

and
http://ford.off-road.com/ford/article/articleDetail.jsp?id=199301

http://tlc.off-road.com/tlc/article/articleDetail.jsp?id=264195

always air up before driving on asphalt again for the safety of others and YOURSELF!!!

 

[post]

if you're running 16x7 rims you probably could air down to 12-14psi safely without worries of popping a bead.

 

[WillTN]

On all of my trucks I run 45 psi all around when on road, two of my trucks have GY MTR's and the other has SSR's. And I almost always air down when I wheel.

(If you air down don't forget to air up at the end of the trail though...)

On my D2 I have 16x8 rims with 245/75 GY MTR's. And I'll air them down to 20 psi, I would not go any lower on an 8" rim with such a narrow tire.
On my RRC and D90 I have 16x7 so I air my tires to somewhere between 15-20 psi, but thats with 32-33" tall tires that are 10.5-11.5" wide.. But I've had tires come off the bead a few times while on the trail...

(Also all alloy rims)

 

[gmookher]

my nato steels are fine in snow at 9 psi..I've been stuck and off camber plenty, luck or not, thus far never an issue(wide lip for the bead)
i dont think I'd go lower than 13 on an alloy myself..

 

[ausdisco]

def no lower than around 12psi on alloys for me,thats for sand though

 

[ozscott]

I usually run 15psi all round on really deep sand thats chopped up to make life easier. I aired them down to 8psi once to get out of a bog in deep sand and then put them back to 15 as soon as I got out.

Cheers

 

[p m]

my nato steels are fine in snow at 9 psi..I've been stuck and off camber plenty, luck or not, thus far never an issue(wide lip for the bead).

Yes, it was luck.

I've lost a bead twice, both times in snow - hitting a rock or a tree branch hidden in snow.
First time it was a 31x10.5, second - 35x12.5, both times - aired down to 18 psi, on 8"-wide rims.

 

[nicky ill]

An easy test for figuring out your onroad PSI is to take a piece of chalk and draw a line all the way across the treads. Drive a short distance, 20 yards and inspect the chalk. If it is wearing away only in the center - you have too much air, and if it wears more heavily around the edges, not enough. Not perfect, but it will get you close to where you need to be based on the weight of your truck. You can finesse it after that.

I can't imagine you being any higher than 40psi, and probably a lot less.

Off-road, experiment, depending on the tire and the load range (d, e, whatever), your needs may differ from other folks. I too run my 265 75 16s (Rated D) at 34 rear, 32 fronts and drop to about 20-22 psi off road.

 

[gmookher]

Yes, it was luck.

I've lost a bead twice, both times in snow - hitting a rock or a tree branch hidden in snow.
First time it was a 31x10.5, second - 35x12.5, both times - aired down to 18 psi, on 8"-wide rims.

exactly why mine are 7" wide its known issue with 8" rims

 

[jimjet]

I run my tires at the L.R. spec regardless of what rubber i have on there.

28 psi front and 38 psi rear with BFG A/T 285/65/18.

I notice a big difference if i go up 2psi from 28 or 38.

i like my ride at the L.R. spec.
I dont airdown on the beach unless we have a long dry spell which is rare .
if i do its 1/2
Jim

 

[p m]

exactly why mine are 7" wide its known issue with 8" rims

There are no "known issues" with 8" rims. All rims we are talking about have the same safety bead groove. You'd want to compare cases with a certain difference between nominal tire width and that of the rim.
I had tires that were at least 2.5" wider than the rim, and they lost beads at higher pressures than you are running off pavement. Given your location, you're on borrowed time off road.
I've had a sidewall slashed in Ouray on a 245/75 on a 7" rim that would not have happened should the tire was up to ~25-28 psi instead of 18.

 

[gmookher]

There are no "known issues" with 8" rims. All rims we are talking about have the same safety bead groove. You'd want to compare cases with a certain difference between nominal tire width and that of the rim.
I had tires that were at least 2.5" wider than the rim, and they lost beads at higher pressures than you are running off pavement. Given your location, you're on borrowed time off road.
I've had a sidewall slashed in Ouray on a 245/75 on a 7" rim that would not have happened should the tire was up to ~25-28 psi instead of 18.

alot is how you place the tires against rocks, get a good spotter and that shouldnt happen
I run Ouray at 16psi all day

I have already accrued over a dozen trips to 8 and 9 rated trails and i mean tough stuff,21 rd here in GJ IS NO JOKE- i had to winch myself thru 20% after robustly reaching for TRACTION, and have led a few trails with multiple riggs, whom i directed to run the same PSI as me, without any issues-even the guys who were hesitatnt to air down eventually did, and they were the ones who asked what pressures i was running...I do inspect the tires, if they are goodyears, or not in good condition/MTs I dont have them air down as low(too much sidewall flex, thin iffy sidewals in my experience on even Goodyear Mts and most ATs). Never air down an AT that low, btw

as you go to a 8 or better yet 10 ply tire, you really gain carcass stiffness

 

[UK 4X4]

80psi........................one word...............POP and that's an understatement.

32 front and rear for me......when loaded the tyre pressures increase..anyway

offroad 17-18psi

I rather not make an obstacle than loose a bead in a remote area

 

[p m]

The sidewall cut I mentioned happened to a 10-ply-rated tire. Right before that almost-flat area before double-bump on Poughkeepsie Gulch.

Most often than not, I wheel without a spotter; half of the time, I wheel alone. I'd rather suffer some tumble on a washboard than replace a tire at 13k ft...