1. Registration trouble? Please use the "Contact Us" link at the bottom right corner of the page and your issue will be resolved.
    Dismiss Notice

Tire Pressure

Discussion in 'Early CJ5 and CJ6 Tech' started by 57cj5, May 24, 2018.

  1. May 24, 2018
    57cj5

    57cj5 Member

    North Carolina
    Joined:
    Aug 31, 2005
    Messages:
    593
    out of curiosity, when I drive my 57 in the am when the air is cool, it drives well, no front wobble. However, in the afternoon, it seems to have a slight wobble at about 45 and above.... Tire pressure? Right now I am sitting at 27 in all 4 (BFG KM2s 15x32x11.5).
     
  2. May 24, 2018
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
    Joined:
    Aug 10, 2003
    Messages:
    23,596
    Maybe. Possible that the profile of your tires changes with increasing temperature. Easy to test ... lower the pressure and see if the wobble goes away. 27 psi is high for a CJ IMO. I run something like 20 front and 16 rear with BFGs in my CJ-6. You can look at the pattern the tire makes and guess at where you are wrt the ideal pressure. Too low and it lifts in the center, too high and it lifts at the edges.

    Note that the closed knuckle axle has some drag built-in, in the form of the greas seals. An open knucle with more freely turning ball joints was routinely fitted with a steering damper by Jeep in the '70s. My '77 J10 (for example) came with a damper from the factory.
     
  3. May 24, 2018
    57cj5

    57cj5 Member

    North Carolina
    Joined:
    Aug 31, 2005
    Messages:
    593
    Thanks Tim...I was thinking in am cooler temps mean lower pressure...higher temps in afternoon mean higher starting pressure. I wasn't sure how low is too low.
     
    Keys5a likes this.
  4. May 24, 2018
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Hills of NH
    Joined:
    Aug 3, 2003
    Messages:
    9,754
    When they come off the rims. :D

    Depends a lot on tire size and vehicle weight. Long thread here recently about determining appropriate pressure. 'Printing' your tires on a flat surface seems to be an approved method for checking street pressure. Sort of a reciprocal of wear patterns.

    But yeah 27psi is high.
     
  5. May 25, 2018
    Daryl

    Daryl Sponsor

    Bonney Lake, WA
    Joined:
    May 25, 2006
    Messages:
    2,871
    I just had to raise the pressure in my Maxxis bighorns. Running 12 psi was starting to wear the blocks a little. I went up to 18 and they seem happier.
     
  6. May 25, 2018
    1960willyscj5

    1960willyscj5 Well-Known Member

    Mesa, Arizona
    Joined:
    Nov 27, 2006
    Messages:
    2,793
    I am old. Grew up before metric tires came into vogue. I learned to inflate my tires to 32 psi all the way around. When the transition to metric started the tire guys never really said anything about running lower pressures, or if they did, it was something like 28 psi. Which felt low to us at the time.
    I still set my tires to 32 psi. And I have been informed lately by the different installers that I should run my tires at close to the maximum recommended pressure on the sidewall. Can be rather confussing, to say the least.
     
  7. May 26, 2018
    sterlclan

    sterlclan Member 2022 Sponsor

    exploring the...
    Joined:
    Feb 21, 2009
    Messages:
    3,869
    I run an lt 235/85/16 load range e ten ply tire the sidewall says 2800 lbs at 80 psi. Not going to happen. I run 22 psi front 18 psi rear get a full contact patch on the ground and great wear.
     
    Daryl likes this.
  8. May 27, 2018
    57cj5

    57cj5 Member

    North Carolina
    Joined:
    Aug 31, 2005
    Messages:
    593
    Do you have a link to the thread or search words?
     
  9. May 27, 2018
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
    Joined:
    Aug 10, 2003
    Messages:
    23,596
  10. May 30, 2018
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Hills of NH
    Joined:
    Aug 3, 2003
    Messages:
    9,754
  11. May 30, 2018
    ronnie victor

    ronnie victor Member

    raleigh, nc
    Joined:
    Jun 29, 2015
    Messages:
    126
    FWIW, my FSM for my 66 CJ5 F4 states in the ''wheels" chapter: 26 psi front; 28 psi rear.
     
  12. May 30, 2018
    Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

    Tantallon, Nova...
    Joined:
    Nov 22, 2003
    Messages:
    8,102
    It's going to depend on tire size- skinny tires take more pressure than wide ones.

    Stock tire sizes in the 60's would have been around 7" or so tread width.

    Standard inflation for NDT's is 32/30 PSI; I run mine at 28/26, anything less than that going around corners gets exciting & not in a good way :(
     
  13. Jun 3, 2018
    Wenaha

    Wenaha Member

    West Coast
    Joined:
    Feb 6, 2014
    Messages:
    415
    This is a very reasonable approach. Almost all tire services, dealer shops, etc. will inflate your tires to max recommended pressure. I am running 215/85/R16 Cooper STT Pro tires (load range E) Running them at the recommended 80 PSI is nuts. I deflate until a get good contact on a flat surface and they feel good driving.

    On mt F350 I am running Goodrich 285/75/R16 ATs. Load range E. I use the same approach to setting pressure, and it usually works out to about 65 PSI (not 80). If I am towing my Airstream or boat, I'll increase rear tires and slightly increase front tires.

    Works for me.
     
  14. Jun 3, 2018
    supertrooper

    supertrooper Member

    moreno valley, ca
    Joined:
    Nov 12, 2007
    Messages:
    742
    I have 33x12.5 MTs and run 22psi on the street. The chalk test that timgr posted is the best way to know what pressure is best for your vehicle.
     
  15. Jun 5, 2018
    CJeep5

    CJeep5 New Member

    California
    Joined:
    Mar 23, 2018
    Messages:
    23
    I have 35x12.50-15 MTR's that I have at 20 psi, well that's where I ran them til I parked her a while back. Now they have probably 10 psi and HUGE flat spots! All to be worked out soon.
     
New Posts