Tire inflation requirements

Discussion in 'Trucking Industry Regulations' started by omaharj, Jun 15, 2024.

  1. omaharj

    omaharj Bobtail Member

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    I'm a fan of quoting statutes when I have a FMCSA question, but I can't find it printed anywhere!
    I've heard a tire is considered underinflated to the point of being OOS when it drops below 50% of the maximum allowed pressure. One guy at work claims it has to be at least 95% of listed pressure. I've always gone with the 50% number (although in practice I top 'em up if they sound funny). I drive to a meet and get trailers with tires at various low points.
    Can anybody quote a statute for me? Thanks.
     
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  3. Arctic_fox

    Arctic_fox Experienced mx13 execrator

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    See paragrapgh I section 1 and 2. Basically whatever the minimum cold rated pressure for the load is is your minimum. To find this info see your owners manual or the sticker on your door. For example.

    20240606_110515.jpg

    For example here you can see what the cold pressures will be for each tire rating for a given size. In sure someone has one for 24.5s and such but in my case running F tires it would be 90 PSI instead of the 110 i keep them at. Or at least that is how I as someone who is NOT a lawyer understands it.

    That said best practice is to add more at 95 PSI and they will generally speaking leave you alone.
     
  4. Lyle H

    Lyle H Road Train Member

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    It actually says that the minimum cold psi must meet the pressure needed for the load being carried.
    In other words, if the tire only need 80 psi to carry whatever that weight specifies, that is the minimum pressure needed.
     
  5. Arctic_fox

    Arctic_fox Experienced mx13 execrator

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    Yes and thats listed on my sticker namely for 19000 pounds on an F rated tire its 90 psi, which is why i said it the way i did.

    That said most manufacturers i checked dont have a list i can FIND keyword veing find that rates tire psi per load weight save max and max. I.E
     

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  6. Lyle H

    Lyle H Road Train Member

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    Michelin had a chart showing minimum pressures needed for various weights in both single and dual applications.
    If the op wants something to show someone for proof that he was not under inflated for that particular load he could print that out.
     
  7. Lyle H

    Lyle H Road Train Member

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    Arctic Fox quoted the statue. Notice it says nothing about “percentages”.
    It says the tire must have the minimum pressure required for the load being carried.
    There are charts out there that will tell you what that number is.
    Print one out for your size tires for reference.
     
  8. Iamoverit

    Iamoverit Medium Load Member

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    Most tire manufacturers have a load rating chart.
     
  9. m16ty

    m16ty Road Train Member

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    I’ve never seen a officer say anything about tire inflation unless one was squatting badly or flat.
     
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  10. brian991219

    brian991219 Road Train Member

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    393.75 covers tires. There are two areas that can cause problems with inflation. The first is operating below the minimum cold pressure for the load (weight) being carried by the tire. The other is the CVSA Out of Service criteria which is found in their published guide (not available unless you buy it from them) which is where the 50% rule comes from.

    For a tire to be placed OOS due to being "flat" it must have an noticable air leak (heard or felt) or has 50% or less of the maximum inflation pressure as show on the tire sidewall. For more information see CVSA Operational policy 15.

    Here is a picture of their 2021 OOS guide, although they replace the guide yearly in April this is still accurate. I just don't have my 2024 guide with me today.

    17185681588237105765277906279504.jpg
     
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  11. Lyle H

    Lyle H Road Train Member

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    There is no maximum pressure listed on the sidewall. Only minimum pressure required to haul specified weight.
    Only the rim has a maximum pressure rating.
     
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