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Air"n Down

Discussion in 'The Garage' started by johnathan, Apr 7, 2006.

  1. johnathan

    johnathan 1/2 ton status

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    I'm runnin some 16'' aluminum simulation beadlocks rims.How far down can I go with air pressure without drasticly increasing the risk of blowing a bead??
     
  2. MTMike

    MTMike 1/2 ton status

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    With 16's I don't know for sure..... I beleive since they're not 16.5's (w/out the safety bead) you should be able to go quite a bit lower than you would with 16.5's.

    My buddy's running 15's and I've seen him air down to 4 or 5 and open up his big block in many feet of snow and still not blow a bead

    Hope this helps, and I'm sure someone else will chime in with more direct experience

    Mike
     
  3. bajaviking

    bajaviking 1/2 ton status

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    It depends on how wide your rim and tires are. If you run a 8" wide rim with 12.50 wide tires I would air down to 8psi with no worries, maybe even lower in the sand. If you run a 12" rim with a 12.50 wide tire I don't think I would go lower than 12 psi.
     
  4. roadnotca

    roadnotca 3/4 ton status

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    Mark the tire with a reference at where the valve is, if/when you remount you can get the balance back, that is if you have lead weights.
     
  5. johnathan

    johnathan 1/2 ton status

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    The rims are 8'' wide.The tires are 285 75 so I would guess about 10'' wide, maybe. I was told when I bought the tires that 285 75 was like a 35''but they are more like a 33''.Live and learn.
     
  6. dremu

    dremu Officious Thread Derailer Premium Member

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    285mm tread is about 11 1/4" wide (285mm/25.4mm per inch = ~11.2")

    On a 16" rim that's 32.8" diameter (nominal, not real), so yup, like a 33".

    315-75-16's are the 35x12.50 equivalent in new-style. (I can't say metric, as only one measurement is in mm, another is in inches, and the third is unitless :mad: )

    -- A
     
  7. Hossbaby50

    Hossbaby50 3/4 ton status

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    It also depends on the tire. You can air down a tire with a stiffer sidewall more then you can air down a tire with a soft sidewall. I ran 35" MTR's on 8" rims on my truck. The lowest I ever aired down was 14psi. With anything below about 17 PSI you started loosing alot of height and started bulging the sidewalls alot.

    I wheeled in the rocks. Some areas had were pretty jagged too so I kept the pressure up between 17-19 in the jagged areas to keep the sidewalls away from the rocks. MTR sidewalls aren't as strong as the "Dura-wall" protection may imply. I smoother rock areas I would go down to about 14-16 PSI.

    If you have a tire like a Swamper SX with a beefy stiff sidewall then you could probably air down to the low double digits or even the single digits without alot of worry. My buddy runs his 42" Swampers on 8" rims at about 6-8 PSI on a heavy truck.

    Harley
     
  8. ankarback

    ankarback 1/2 ton status

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    I was running 10psi and lost a bead on the right rear tire last weekend. 8x16 M/T Classic II Wheels and 305/70-16 BfG mud tires. Never had this problem when I was running whitespoke steelwheels so I guess it depends a lot what kind of wheels you are running.
     

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