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Air pressure in tires

Discussion in 'XJ Technical Chat' started by wonderdawg, Jan 12, 2010.

  1. wonderdawg

    wonderdawg Member

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    I was just wondering what the air pressures should be in my front and rear tires? I am currently running 25 psi in the front and 34 psi in the rear according to my service mannual this low for both the front and rear. It reconmends 32 psi front and 36 psi rear. Any thoughts on this subject. Also how much could this be affecting my fuel economy???

    Regards,

    W. D. :eek:
     
    wonderdawg, Jan 12, 2010
    #1
  2. lopezfr2

    lopezfr2 Member

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    max load should be printed on the side of the tire. mine both say 40 max
     
    lopezfr2, Jan 12, 2010
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  3. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    If your book says 32/36 then I would go with 32/36. Soft will lower fuel economy. How much, it's hard to say. Why not get some accurate mileage numbers, then make the change and watch the mileage.
     
    bigfitz52, Jan 12, 2010
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  4. SLKid

    SLKid Active Member

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    I've also been kinda curious about PSI. Mine both say 40 max as well, so I usually do both at 35. Would increasing one and decreasing the other affect performance and Handling? Hmm
    -Chris
     
    SLKid, Jan 12, 2010
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  5. iwingameover

    iwingameover Active Member

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    Yes. Lower air pressure allows the sidewalls much more flex. It also gives a bigger contact patch on the ground.
     
    iwingameover, Jan 12, 2010
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  6. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    Correct. 35lbs is way too stiff for the fronts on most bikes; better to go by the manual than the "max" on the tires.
     
    bigfitz52, Jan 12, 2010
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  7. SLKid

    SLKid Active Member

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    Book says 28 Front and 40 Rear for back for me and a Passenger, and High Speed Riding was 30 32. Interesting. I'm thinking a medium of 30 35. Cool. Ty guys
    -Chris
     
    SLKid, Jan 12, 2010
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  8. wonderdawg

    wonderdawg Member

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    Okay cool good to know. I had inflated them last night to what I thought was the correct PSI, and then checked them again this morning. That way I knew the tires were cold. I will just have to keep tract of the handling and fuel economy. I will try to follow up with you all.

    Regards,

    W. D.
     
    wonderdawg, Jan 12, 2010
    #8
  9. DaveXJ

    DaveXJ Member

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    You always go by what the vehicle recomends not what the tire says. Every bike/auto weighs different.
    Mine are the same as SLkid 28/40
     
    DaveXJ, Jan 12, 2010
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  10. wonderdawg

    wonderdawg Member

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    Ok here are the results from my first tank. It has rained here over last couple of days and I do not like to ride in the rain. I had respectfully increased the air pressure in the front significantly and the rear only slightly. But since the holidays are over with and kids are back in school the traffic is back to its normal crazy pattern of stop and go,... go, go, go and stop.

    Prechange: 41 MPG average

    Post-Change: 44 MPG

    Regards,

    W. D.

    8)
     
    wonderdawg, Jan 17, 2010
    #10

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