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Lowering Tyre Pressures

Discussion in '40- & 55-Series Tech' started by Guest, Apr 16, 2003.

  1. Guest

    Guest Guest

    Why is it that some peolpe Lower their Tyre Pressure for other than Sand? :stupid:

    I have 44psi in my 31x10.5 Silverstone AT-117(Malaysian Gravel Rally Tyre) :slap:

    I have only ever driven on Sand in my Dads FZJ80R with 270/70R16 Yokohama Geolander H/T GO38 and Lowered the Tyre pressures from 48psi to 30psi.

    In the very soft Sand I used High Range Second Gear at 1,000rpm and was not even close to getting bogged. :)
     
  2. woody

    woody Internet Fireman Staff Member

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    http://www.4x4now.com/sfjun96.htm (from the ih8mud.com tech links section)

    contact area = traction and flotation. I run 2psi rear and 3psi front on my 38.5 SX's in snow situations and 4psi rear and 4.5 or 5 psi front in all other situations. For "daily" drive use (which is rare), 12 front and 10 rear. My truck weighs 4100#, the tires are rated for 3700# at 30 psi EACH...that's ~15,000# rating for the 4 tires....

    Additionally, having the tires that low for offroad use allows them to wrap around the little rocks and greatly smooth the ride.

    Tire (or tyre) pressure is an experiment, but the link above does a good job of covering it.
     
  3. Niner

    Niner

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    a couple of examples would be NASCAR, they use it more for stagger to make the car turn. Maybe a better example would be drag races, if you watch the top fuel rails their tires grow considerable when they do their burnout, but hardly spin once they get the green because the flat (2 psi) wrinkles adhearing to the track. The same laws of friction apply to dirt.
     
  4. IDave

    IDave

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    I think this is an interesting topic.  I appreciate Brian's reference to the tech article, which to me makes a lot of sense.  I was wondering what other people are using for their tyre pressures.  I noticed that my '71 owner's manual recommends 17 psi for "sand driving", 26 psi for normal driving, and 28 psi for "high speed" driving, whatever that is supposed to be in an FJ40. Thats obviously for stock tyres, and numbers would change with different diameters.