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Tire Pressure

Discussion in '80-Series Tech' started by mtycruiser, Mar 5, 2004.

  1. mtycruiser

    mtycruiser

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    After a lot of thinking and some advise from the forum, I opted for the BFG's instead of the Revos for my '98 UZJ100. Previous tires were MIchelin Cross Terrain.

    First impressions:
    1) At 32 psi they are a lot stiffer and don't seem to bulge at all :(
    2) Truck looks a lot better :)
    3) They make substantially more noise relative to the Michelins, which are passenger rated highway tire.
    Questions:
    a) What air pressure are you running on them for Highway and for trail riding
    B) how low you while airing down?
     
  2. Beowulf

    Beowulf

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    >> Questions:<<
    >> a) What air pressure are you running on them for Highway and for trail riding
    >> B) how low you while airing down?

    When I had the BFG A/T's they stayed at 40psi for street driving. Typical air down for off-road was to 18psi depending on terrain. Sometimes 10-12 psi in snow.

    -B-
     
  3. Junk

    Junk

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    I run my BFG AT/KO 295/75r16's at 42psi on the road and don't take them offroad. If I do go offroad with them, it's not on a real trail, so I haven't aired them down yet.

    I would advise to slowly play around with the pressure and find what you like best.
     
  4. Landpimp

    Landpimp

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    I am at 32 and 30psi on mine, but I haven't played with em much yet.
     
  5. TLCObsession

    TLCObsession

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    32 all the way around. take them to 18 in the snow and the few trails it sees.
     
  6. SIDSTOYS

    SIDSTOYS

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    I've only had my BFG AT/KO 295/75/16's into my third week of highway driving with no off road as yet on the '95. Played around with 30, 35, 45, and 55 psi thus far. I personally like the ride at 55 best and have stayed with that for now on dry and wet pavement and lots of deep to shallow unfilled pot holes from winter winding down here in the East mid-Atlantic. Personal preference would dictate I suppose.
     
  7. FJ60

    FJ60

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    ;)

    and to think I raised hell over the oil change monkey's airing my BFG's up to 40 psi :-\ I thought 30-32 was more than enough???
     
  8. mtycruiser

    mtycruiser

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    I'm also surprised at the high pressures some of you are reporting, they certainly help in rolling resistance, but how about riding harshness??
    Aren't you jumping around all over the place with those pressures??
     
  9. Landpimp

    Landpimp

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    open the drivers door.........look at the sticker........thats where I started ;)
     
  10. Bob_Garrett

    Bob_Garrett

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    Ran a set on my 80 for over 25k mi and kept them at 36-38psi on the highway and about 20-24 for off-road (only ran easy trails with them). Rotated every 5k and had even wear with about 15/32 tread left after 25k mi.

    Bob
     
  11. mtycruiser

    mtycruiser

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    Quote:
    open the drivers door.........look at the sticker........thats where I started

    Me too...actually, that's where I'm at now and starting to play to find the best balance on ride, wear, etc.
    It's interesting however to see what others are doing with the same tire and same vehicle, and as I said, I'm surprised at the high pressures some of the folks use. Years ago I used to have a Grand Wagoneer with 31" tires and I usually run it with 24 psi on city/hwy for comfort (lots of potholes where I used to drive)
     
  12. Landpimp

    Landpimp

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    I was just givin ya s*** ;)

    On my BFG 33x9.5x15 which I run on 3 other Cruiser the max presure is 50psi........holly cow there is no need for that high IMOP, I run 30ish in most of em.

    I recall a good way to find the correct presure for your rig is to, check presure when cold, then drive for a bit(till tires warm up) then check, if the presure has gone up your presure is too low, so repete till it doesn't raise when warm. I am sure there are varibles to this, but its might be a good way to start as well, its suppose to make your tires the happiest.....but might not be right for the way you drive or the ride you like.

    John H


    [quote author=mtycruiser link=board=2;threadid=12594;start=msg115954#msg115954 date=1078528368]
    Quote:
    open the drivers door.........look at the sticker........thats where I started

    Me too...actually, that's where I'm at now and starting to play to find the best balance on ride, wear, etc.
    It's interesting however to see what others are doing with the same tire and same vehicle, and as I said, I'm surprised at the high pressures some of the folks use. Years ago I used to have a Grand Wagoneer with 31" tires and I usually run it with 24 psi on city/hwy for comfort (lots of potholes where I used to drive)
    [/quote]
     
  13. scottm

    scottm

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    [quote author=Landpimp link=board=2;threadid=12594;start=msg115959#msg115959 date=1078528779]repete till it doesn't raise when warm.[/quote]
    I'm pretty sure that violates the laws of physics, air expands when warmed. My tires often steam on rainy days when I pull off the highway for gas.
     
  14. Landpimp

    Landpimp

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    OK.......so I forgot part of the formula.........maybe it was to it raises no more than 2psi.....loosing my memory fast, partial to blame is the sinus infection that pounding my head :'(

    [quote author=Scott M. link=board=2;threadid=12594;start=msg116029#msg116029 date=1078534289]
    I'm pretty sure that violates the laws of physics, air expands when warmed. My tires often steam on rainy days when I pull off the highway for gas.
    [/quote]
     
  15. semlin

    semlin discouraged user

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    I like 40 psi on my 31" bfg Ats in town, having tried in the 30s and 60's (yes in the 60's thanks to my ex mechanic -- I wondered why I was bouncing around). I find about 22 is perfect for a washboarded logging road. Not sure if the sidewalls are strong enough to take being aired down into the teens when holding up an 80. There is a formula to figure out the drop in weight bearing capacity as pressure drops from the psi rating on the side.
     
  16. DoggieStyle

    DoggieStyle

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    wake up people. You can not compare tire pressure with different size tires. Every size has different load capacity. the guy was asking about 285/75R16. Your answers were from all different sizes. That will confuse the nice fella who asked the question in the first place. It will also depend on how much your truck weighs. If you carry 800 pounds of horsecrap around with you the correct pressure will be higher than an empty truck.

    Look at the way the tires wear over time. If it's even across the tread you're probably in the right place.

    Offroad pressures are stricly reletive to the speed and terrain and weight. One size does not fit all.
     
  17. Landpimp

    Landpimp

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    hey bucko my 1st reply was about 285/75/16 BGF AT on a 100 so................ :flipoff2:

    but your correct :D



    [quote author=DoggieStyle link=board=2;threadid=12594;start=msg116111#msg116111 date=1078541426]
    wake up people. You can not compare tire pressure with different size tires. Every size has different load capacity. the guy was asking about 285/75R16. Your answers were from all different sizes. That will confuse the nice fella who asked the question in the first place. It will also depend on how much your truck weighs. If you carry 800 pounds of horsecrap around with you the correct pressure will be higher than an empty truck.

    Look at the way the tires wear over time. If it's even across the tread you're probably in the right place.

    Offroad pressures are stricly reletive to the speed and terrain and weight. One size does not fit all.
    [/quote]
     
  18. Riley

    Riley

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    driving on road aired down

    I'm wondering about how bad is it to drive on the highway with aired down tires?

    For example: Some of my favorite off-roading places are about 50 miles from town on the pavement and that's where the closest service station is. After airing down to say 22 lbs (on 305/75 MTRs), can I drive on the secondary hwy at 50 mph for say 50 miles without major issues?

    I'm assuming I'd be wearing the tires a lot?

    also handling would suffer, anything else?

    You guys do this or does everybody air up at or near the trail head?

    I'm trying to figure out when I need to get some on-board air or can I delay this expense for another year or 2.

    I also carry a fair amount of gear so I guess this adds to the issues encounter.

    What about going lower, say 18 lbs?
     
  19. firetruck41

    firetruck41

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    I think the biggest problem is heat, which increases dramatically (at road speeds) as you lower your pressure, which could cause failure, not just tread wear.

    Just buy a cheap 12V compressor from wal mart, will take a while but probably can at least get you to a safe pressure.
     
  20. Riley

    Riley

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    I've got one of those cheapies already. It's pretty painful to use. Been thinking about rigging up on board air with a good compressor from Slee. Maybe that's what I should do,
     
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