What PSI should I set my tires at?

Discussion in 'Motorized Vehicles' started by The Fire Snake, Apr 6, 2010.

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  1. The Fire Snake

    The Fire Snake Notebook Virtuoso

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    I have a normal set of tires with a max PSI rating of 32 and I have some low profile tires with a max PSI at 50. What PSI should set them at so that I have optimum fuel mileage, comfort, safety to the rim etc? Is there a rule like set it to 4 PSI below max? Thanks.
     
  2. millermagic

    millermagic Rockin the pinktop

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    The car companies usually have them set a bit low for comfort. Fuel efficiency would be at max psi as stated on the sidewall.

    The way it's supposed to work is higher pressure gives better mileage, but reduces traction and wears the center of the tire. Lower pressure does the opposite.

    My car is so out of alignment (and front suspension so worn out that it can't be aligned) that it eats out the tires quick. I just run at the max on the sidewall and call it a day.
     
  3. aan310

    aan310 Notebook Virtuoso

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    4psi under is what we do at my shop.
     
  4. maozdawgg

    maozdawgg Notebook Geek

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    From what I understand, higher tire PSI is less wear and tear and higher MPG but at the cost of a bit less traction because less rubber is in contact with the road due to the higher PSI ("slimmer tire width") and so there is less rolling resistance.

    Lower PSI leads to greater traction but more wear and tear as well as reduced MPG due to more rubber in contact with the road (flabby/wider tire) and hence more rolling resistance.

    This is the first time I've heard of the 4PSI rule, and not sure the reason behind it. Could it be to generate more sales at shops and retailers to sell products (tires) and services (tire change) ? Or maybe I'm being too cynical.

    Personally, I keep my tires at around 38-39 PSI for the less wear/tear and the higher MPG. But if any tire expert wants to chime in please do so if it is better or worse to keep a tire at higher vs lower PSI.
     
  5. merlin2375

    merlin2375 Notebook Consultant

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    The PSI rating on the sidewall is the maximum that the tire can withstand. I would never set my tires at or even really near this level.

    I always set my tires to the manufacturer recommended PSI. This can be found on a sticker that is typically on the driver's door jam. Sometimes, the sticker is in the center console, etc. The manufacturer arrives at this number through testing. Granted, it may not be slightly lower for comfort they also look at the MPG numbers very closely in their testing. Traditionally, the numbers on the sticker apply to the stock tire size but it should also be a good number of other tire sizes.
     
  6. Tinderbox (UK)

    Tinderbox (UK) BAKED BEAN KING

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    Hmm , I have never see the tyre pressure on a car tyre in the UK , on bicycle tyres yes, it sounds like a good idea though.

    EDIT : maybe it`s because it depends how much weigh is on the tyres , front of the car heavy engine needs more pressure? , so it`s best to check the manufactures pressure recommendations.
     
  7. houstoned

    houstoned Yoga Pants Connoisseur.

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    that's not a good rule of thumb to follow. different tires will require different psi levels. u can't put the same amount of air into a 275/25/20 sized tire as a 195/60/20 sized tire.

    just make sure u always fill yur tires when they are cold and follow what's on the sidewall. the manufacturers put it on there for a reason. i follow the 4-5psi below max rule as well. that 4-5psi is a cushion they recommend cuz the air in yur tires will expand a bit after u start driving. u know...it's that physics stuff. rotation = friction = heat = blah blah blah
     
  8. Trottel

    Trottel Notebook Virtuoso

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    Half the reason I never let a shop touch my cars!

    It actually is a good rule of thumb for the average consumer. The car manufacturer probably has a good idea when they recommend tire pressure. Also different tires DO NOT require different pressures. Pressure does not equal volume.

    The tire manufacturer's pressure rating is not a recommendation of what you should fill it up to. It is there as a warning not to exceed that pressure. If you buy new tires (not at a shop that puts them on your car) they always come with an information packet and in that packet is says to follow the car manufacturer's advice on tire pressures.
     
  9. houstoned

    houstoned Yoga Pants Connoisseur.

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    i've owned alot of tires ranging from regular passenger tires to barely DOT-certified drag radials on my cars. i always fill them up to 4-5 psi below the recommended max. the only time i would ever run them any lower is when i'm racing and i need some extra traction or the weather is crap. when it comes to performance tires, different companies use alot of different sidewall technology and thicknesses that affect recommended psi. my last rims were 20" x 11" with a 275/20 or 25/20 tire. the max psi rating was like 60 or higher on my toyo t1r's. i would never ride a low profile tire around the 30-40 psi range. that's just askin for bent rims.

    if u are just using an OEM-sized tire, then sure, go with the suggested OEM ratings. once u start playing with different sized wheel and tire combos then the playing field starts to change alot.
     
  10. millermagic

    millermagic Rockin the pinktop

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    The recommended pressure on the door jamb is for ride quality. On trucks, the recommended empty is one pressure and the recommended full is the max on the sidewall.

    Ford Explorers were safer with the tire pressure at the max.

    On my car I run the fronts at 38 (max is 40) and the rear at 32 (the recommended). More weight on the front so it gets more pressure.
     
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