PSI question?
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Suspension, Brakes and Tires Discussion, PSI question? in Item Specific Cadillac Discussion; my tires are rated for 44 psi, the tires are fairly new, but when i fill them to 44 psi, ...
  1. #1
    CaddieMan709 is offline Cadillac Owners Member
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    Question PSI question?

    my tires are rated for 44 psi, the tires are fairly new, but when i fill them to 44 psi, they still look really under inflated... there is no air leak they hold their pressure but i filled one up, it doesnt look full and to the right pressure until it hits 49/50 psi, so should i leave the tire at 44 psi or eyeball it?? im not getting new tires when these tires arent old and have plentry of tred left of them
    im thinking ever since i just filled them to 44 psi and they look under inflated thats why im losing gas milage, any ideas??

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  3. #2
    carnut is offline Cadillac Owners Master
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    Re: PSI question?

    This inflation misinformation has been around for at least 75 years. Inflate the tires to what the decal on the car says. The MAX inflation stated on the tire itself relates to at what PSI the tire can safely be inflated cold before blowing up! The tire has no idea what car it has been installed on. The car manufacturer does the research to come up with a pressure that is #1 safe, #2 best compromise for wear and ride. Then it gets posted on a decal on door jamb, gas filler lid or door post depending on who makes the car. Adjusting 2 to 5 lb. from the decal for added weight can help make the tire last longer and run cooler. Every tire regardless of what car it eventually gets put on has a MAX pressure stated on the side wall as a liability protection so some idiot doesnt just keep adding air till it explodes. Newer radial tires are designed to flex on the sidewall to aid in better cornering traction. To the newbie they will, if fact, look under inflated.

  4. #3
    CaddieMan709 is offline Cadillac Owners Member
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    Re: PSI question?

    Normally i would read the sidewall and go by that, the only reason i questioned it was because it seems to a lot less inflated than what it previously did, even tho the pressure gadge tells me its staying the same, and no, the temperate outside has been the same for the past couple months so its not getting colder outside, normally i wouldnt have said anything

  5. #4
    codewize's Avatar
    codewize is offline Cadillac Owners Master
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    Re: PSI question?

    carnut is correct. The number on the sidewall is the MAX the tire can be inflated to safely. Don't use that number or you'll most likely wear tires like crazy and decrease handling causing your car to become unsafe and unstable.

    Inflate to the recommended pressure on the door sticker.
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    Krashed989's Avatar
    Krashed989 is offline Cadillac Owners Connoisseur
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    Re: PSI question?

    The sticker is NOT correct however if you use a tire that does not have some of the stock specifications such as weight rating and maximum PSI rating on the tire. I believe that the maximum PSI rating on the stock tires was 35psi. So for a 4600 pound vehicle (such as my eldo), distributed evenly (I know it's not, but I forget what the weights were in the front and back so I'm just going to say evenly distributed.) would mean that 1150 pounds are on each wheel. That means that the tire has to be able to lift at least 32.87 pounds for every PSI in the tire.

    So lets say you just bought a tire with a load rating of "86". That code means that each tire can lift 1168 pounds. Now lets say that it has a maximum PSI rating of 44psi. That means that for every psi in the tire, it can lift 26.55 pounds. So going by the sticker's 30psi would only have the tire lifting 796.5 pounds of the 1150 being place on it. That tire would be underinflated.

    This is why it really depends on the load rating/psi rating of the tire you're using.

  7. #6
    krimson_cardnal's Avatar
    krimson_cardnal is offline Cadillac Owners Enthusiast
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    Re: PSI question?

    Door Sticker PSI is for the OEM set-up. ALWAYS look at your tire on a clean, smooth, level surface. Inflate to 36PSI and look at it. Bump it up to 46PSI look again. My guess is over inflation. Better MPG. Wear centered on tread. Hard/Firm ride.

    COOL Inflation:
    36PSI - front
    34PSI - rear

    96DeVille

  8. #7
    CaddieMan709 is offline Cadillac Owners Member
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    Re: PSI question?

    ok i read the door, it said 35 psi for tires, i did it, the tires dont really look much different than when i had them at 42 psi i suppose, the only problem is im getting a LOT more squeeling going around corners and accelerating, and by no means am i whiping around corners, just at a normal pace and its starting to bug me, is this normal? if not im going to fill them up a little more, im cant listen to that squeeling all the time

  9. #8
    MashBill's Avatar
    MashBill is offline Cadillac Owners Member
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    Re: PSI question?

    Quote Originally Posted by CaddieMan709 View Post
    ok i read the door, it said 35 psi for tires, i did it, the tires dont really look much different than when i had them at 42 psi i suppose, the only problem is im getting a LOT more squeeling going around corners and accelerating, and by no means am i whiping around corners, just at a normal pace and its starting to bug me, is this normal? if not im going to fill them up a little more, im cant listen to that squeeling all the time
    What brand, model, and size are they?

  10. #9
    krimson_cardnal's Avatar
    krimson_cardnal is offline Cadillac Owners Enthusiast
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    Re: PSI question?

    Bring 'em up to 38PSI lower rears a bit. Don't fear finding the best pressures for your set-up. Be objective to a point then go by seat of the pants feel. K_C

    Quote Originally Posted by CaddieMan709 View Post
    ok i read the door, it said 35 psi for tires, i did it, the tires dont really look much different than when i had them at 42 psi i suppose, the only problem is im getting a LOT more squeeling going around corners and accelerating, and by no means am i whiping around corners, just at a normal pace and its starting to bug me, is this normal? if not im going to fill them up a little more, im cant listen to that squeeling all the time

  11. #10
    CaddieMan709 is offline Cadillac Owners Member
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    Re: PSI question?

    haha thanks, and MashBill they are Goodyear Allegra P225

  12. #11
    MashBill's Avatar
    MashBill is offline Cadillac Owners Member
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    Re: PSI question?

    Quote Originally Posted by CaddieMan709 View Post
    haha thanks, and MashBill they are Goodyear Allegra P225
    Thanks. I'm not familiar with that tire and I can't find any data on it.

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