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e-rated tire pressure

Discussion in '3rd Gen. Tacomas (2016-2023)' started by Teal_6, Jan 14, 2021.

  1. Jan 15, 2021 at 11:34 AM
    #41
    tonered

    tonered bartheloni

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    I recommend the Ignore button. It cleans up the BS in the 3rd Gen section.
     
    71tattooguy likes this.
  2. Jan 15, 2021 at 11:34 AM
    #42
    coopcooper

    coopcooper certified youtube mechanic

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  3. Jan 15, 2021 at 11:39 AM
    #43
    71tattooguy

    71tattooguy Well-Known Member

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  4. Jan 15, 2021 at 12:37 PM
    #44
    Teal_6

    Teal_6 [OP] Well-Known Member

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    Where’s the ignore button. And yes everyone stop the keyboard warrior fighting. I welcome helpful insites. For the time being I’ve aired my tires up cold to 27 and 26 so when warm they will be 30 and 29. The tpms light is off when cold and it’s in the 30s here
     
    tonered[QUOTED] likes this.
  5. Jan 15, 2021 at 12:39 PM
    #45
    tonered

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    Click the user name, and it's here:
    upload_2021-1-15_12-38-48.jpg
     
  6. Jan 15, 2021 at 1:50 PM
    #46
    rlx02

    rlx02 ¯\_(ツ)_/¯

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    I asked you what do you recommend in determining what tire pressure you should run yet you have not given any recommendations or any information I can read about as to why chalking is a useless method. A quick search doesn't reveal any articles as to why you shouldn't use chalk.

    So again, I ask you what should I use to determine what tire pressure to run my tires, when there is only a max PSI rating by the manufacturer?
     
    tonered likes this.
  7. Jan 15, 2021 at 2:04 PM
    #47
    BRFab

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  8. Jan 15, 2021 at 2:15 PM
    #48
    tonered

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    Good info.

    The only problem is that it seems to work on balancing the load rating. At best I would say that is a good starting point, esp if hauling / towing near the GCVW?

    Day to day / DD use, my butt dyno is taking over. :D
     
    Teal_6[OP] likes this.
  9. Jan 15, 2021 at 2:23 PM
    #49
    splitbolt

    splitbolt Voodoo Witch Doctor

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    I prefer the "inflated load capacity" or chart method, based off recommended psi.

    I dislike the chalk method because:
    -It's a throwback to the days of bias plies; modern radials don't react the same...especially LTs
    -It doesn't account for dynamic loading of the tire. Stock tires are inflated to 8,600 lbs; Tacoma GVWR is 5,600. That's a 1.54 dynamic load factor
    -Can easily be misread, done improperly or incomplete. The chalk method I'm familiar with, you're supposed to overinflate and deflate down to the equal footprint, add 10%, then match deflection of the highest tire and finally, test drive at 55 mph from 'resting' psi, looking for no more than a 10% increase after 10 minutes. These additional steps are meant to account for dynamic loading.

    More...https://www.tacomaworld.com/threads/lt-tires-pressure-and-mpg.626207/#post-21603024
     
    Last edited: Jan 15, 2021
    Teal_6[OP], rlx02[QUOTED] and tonered like this.
  10. Jan 15, 2021 at 2:28 PM
    #50
    tonered

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    Motorcycle folks love this one. I've always been too lazy to verify.

    Luckily, the tires that I am using feather badly unless I am up 2psi cold. I like it when easy and lazy collide in my favor.
     
    splitbolt[QUOTED] likes this.
  11. Jan 15, 2021 at 2:41 PM
    #51
    Sungod

    Sungod Well-Known Member

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    Since I feel helpful today, please take a look at this video - Top Fuel Slowmotion Burnout - YouTube Notice that the tires totally change shape as they spin. Now granted this is a 1000hp dragster with bias ply tires that are 17in wide, but you get the idea. It would be completely pointless to put chalk on those tires and roll around a parking lot thinking that you would be able to optimize the pressure from a 10mph ride. The same thing that you see with that video happens to your truck as you drive. The faster you go, the more the tire distorts. Just like the water balloon example that you seemed to not understand. This along with probably 10 other factors render the chalk test total nonsense. Just because people continue to repeat something doesn't make it fact. The reality is that it is one of those things that doesn't do any harm and doesn't cost anything so most people don't give it much thought. I mean you will likely never see any harm from it, but in reality it tells you nothing.

    As for interco. Take a look at their headquarters - 2412 Abbeville Hwy - Google Maps I'm sorry, but not exactly the type of place I would be citing any auto expertise from.
     
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  12. Jan 15, 2021 at 2:48 PM
    #52
    rlx02

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    I understand why the reason behind top fuel drag racers. I was referring to street cars and airing down to find the best contact patch for launching. Also, we would use chalk or paint markers on our sidewalls when autocrossing to increase pressure if necessary (when hot) to ensure that we had the best contact patch.

    As for interco, welp can't argue with that.
     
  13. Jan 15, 2021 at 2:54 PM
    #53
    tonered

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    Measurable distortion from rotational inertia against 1,250lb per corner at 650rpm. :rolleyes:
     
  14. Jan 15, 2021 at 2:55 PM
    #54
    rlx02

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    I read your post but it's still a bit confusing. So I'm running p-metric tires (285/70/17 - 2755@50psi )and if I do the math (which I'm terrible at), I should in theory be running these at 40psi, if I had stock weight?
     
  15. Jan 15, 2021 at 3:08 PM
    #55
    splitbolt

    splitbolt Voodoo Witch Doctor

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    Are you certain it's a P-metric and not a euro-metric? They have a "P" prefix...P285/70/17/117?
     
  16. Jan 15, 2021 at 3:32 PM
    #56
    Marshall R

    Marshall R Well-Known Member

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    I don't think you have a tire pressure issue. You just have some rough riding tires and suspension. Playing around with the amount of air in them isn't going to significantly change anything.

    FWIW I have E rated LT265/75/16's on my Tacoma @ 30 PSI. They ride just fine. I just have a better riding tire along with the factory suspension. Anytime you go to a wider, larger tire it is harder to get everything to balance out and ride good. You have to take the good with the bad, if you want bigger tires and a modified suspension you're going to have to live with a rougher ride. There is no free lunch.

    And I don't care what anyone says, the chalk test, or something similar provides usable information. I rarely actually go to the trouble to chalk the tires, but after driving on a dirt or muddy road and getting back on pavement you can drive a short distance and observe your tires. If the mud or dirt is still on the edges of the tires they are over inflated and your tires are not making full contact with the ground.
     
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  17. Jan 15, 2021 at 3:32 PM
    #57
    rlx02

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    Sorry, just double checked and they are LT.
     
  18. Jan 15, 2021 at 4:20 PM
    #58
    splitbolt

    splitbolt Voodoo Witch Doctor

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    This is the load chart for your stock tire.
    It's a euro-metric, 265/70/16/112SL.
    At the recommended psi, you have an inflated load capacity of 2,149 lbs.
    tire1.jpg
    P-metric and euro-metric tires are de-rated by a factor of 1.1 for use on trucks and SUVs.
    LTs are not de-rated.
    LTs require (2,149/1.1)=1,954 lbs inflated load capacity.


    This is the chart for a LT285/70/17. You can see 1,954 lbs is "off the chart", but close enough we can extrapolate a value for 1 psi from the 35-40 psi range.
    2,315-2,105=210 lbs
    210 lbs=5 psi
    42 lbs=1 psi

    3 psi backward from 35 psi @ 2,105lbs...
    2,105-(42x3)=1,979 lbs
    32 psi gives you an inflated load capacity of 1,979 lbs

    tire2.jpg
     
    rlx02[QUOTED] likes this.
  19. Jan 15, 2021 at 4:25 PM
    #59
    rlx02

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    This is great info. Although funny enough 32 psi is what I currently run, as I've found it's the best for comfort/handling and mpgs.
     
    splitbolt[QUOTED] likes this.

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