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Tire Pressure Carrying Hawk on Tundra w E-Coopers


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#31 klahanie

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Posted 07 February 2019 - 10:06 PM

I want to reconsider my first reply to the OP  ...

 

To recap, I suggest 2 methods, or a blend there of, and the applied results to be monitored with a tire gauge [ON EDIT: tire tread depth gauge] :

 

1) match the vehicle placard values per the doc linked in this thread, as prev posted. Likely the placard psi posted for the OE size will calculate out to a higher value than the respective GAWR. This overage I'll call the load reserve. This seems to vary quite a bit for different vehicles. In rubberleg's case it works out to 141% FR / 125% RR (my calc from data given). For my truck it is 107% FR / 103% RR. The auto mfrs have their reasons for this - I don't pretend to know them all. (fwiw tho, I'm not certain that the construction and target application of a LT tire would motivate the same reserve allowance as a P metric might.)

 

If the vehicle axle weights are within the GAWRs then the equivalent mfr load reserve is included in the matched psi for the new size/type, per doc. If actual wt is higher, increase the look up wt by the load reserve % and find a new psi using the tables.

 

2) use your actual axle wts to find min required psi for your size, per the tables. This is minimum psi, can add more as desired, eg. perhaps 4 psi for highway. NOTE: after some reading I believe 35psi is the min suggested for LT tires.

 

Long story short - by my guess - this could put the OP at 35-49FR / 42-49RR. A broader and higher range than my first post implied. YMMV

 

Final Word. There lot's of info online. This comment I found interesting, proving me wrong once again. source: Nitto TB

 

"LT tires do not offer any benefits of being "heavy duty" when under-inflated."


Edited by klahanie, 07 February 2019 - 10:20 PM.

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#32 rubberlegs

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Posted 08 February 2019 - 05:30 AM

That last link you posted is really informative, thanks.

 

This one, however, indicates that if you drive slower, you can carry more load at low pressures. It seems to be all about temperature. 

 

http://download1476....Load_Charts.pdf

 

I'm not sure how this applies off road yet. Anecdotal stories say that E rated tires are tougher off road, presumably because of more or thicker plies. This is at low speed and sometimes at pressures much, much less than the tables. Today at our FWC dealer, one of the techs said they go as low as 6 psi on snow (and don't seem to pop the bead). He recommended 12-15 psi front and 20 rear after eyeballing our truck. Instead of sidewall life, it seems to be about puncture resistance.


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#33 Wallowa

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Posted 08 February 2019 - 04:53 PM

OP here.  First I do appreciate and respect the opinions put forth in this thread. 

 

To let you know why I have not been commenting on these posts is that I limit my internet time to one day a week, Friday.  This is my only “social media” conduit and I find that the internet by and large is for me a time and energy killing event. 

 

My original inquiry was for first hand experiences of those using “E” tires of the size and hopefully brand of tire in that post.  Specifically what pressures for a comparable load off road do you use as a standard starting tire pressure with “E” rated tires.

 

Being a vintage person, old, my background leads me to trust more in experiential information that theoretical.  In the protracted process of “higher education” degrees I too have engaged in mathematical gymnastics but still trust more in real world events and outcomes. Nothing is so simple that it can’t be made more complex.  Try OODA to unravel knotty questions.

 

I will close with this advice; if possible and if you are inclined read the excellent books on off road preparations and techniques by Chris Scott or Tom Sheppard.  I have found their information has been spot on and of great value for my off road adventures both on my dirt bikes and Tundra/Hawk.

 

FYI…higher tire pressures do help prevent, not eliminate, punctures for several reasons.  And for my off road use and load the tire pressures listed on the vehicle door plate are NA.

 

Again thanks for all the input, it has been of value and appreciated.  And of course I could be wrong. :D

 

Phil


Edited by Wallowa, 08 February 2019 - 04:53 PM.

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#34 Advmoto18

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Posted 08 February 2019 - 05:19 PM

OP here.  First I do appreciate and respect the opinions put forth in this thread. 

 

To let you know why I have not been commenting on these posts is that I limit my internet time to one day a week, Friday.  This is my only “social media” conduit and I find that the internet by and large is for me a time and energy killing event. 

 

My original inquiry was for first hand experiences of those using “E” tires of the size and hopefully brand of tire in that post.  Specifically what pressures for a comparable load off road do you use as a standard starting tire pressure with “E” rated tires.

 

Being a vintage person, old, my background leads me to trust more in experiential information that theoretical.  In the protracted process of “higher education” degrees I too have engaged in mathematical gymnastics but still trust more in real world events and outcomes. Nothing is so simple that it can’t be made more complex.  Try OODA to unravel knotty questions.

 

I will close with this advice; if possible and if you are inclined read the excellent books on off road preparations and techniques by Chris Scott or Tom Sheppard.  I have found their information has been spot on and of great value for my off road adventures both on my dirt bikes and Tundra/Hawk.

 

FYI…higher tire pressures do help prevent, not eliminate, punctures for several reasons.  And for my off road use and load the tire pressures listed on the vehicle door plate are NA.

 

Again thanks for all the input, it has been of value and appreciated.  And of course I could be wrong. :D

 

Phil

Phil

 

Actually, for off-road, lower air pressure vastly reduces the potential for tread punctures on modern tires due to tread conforming to obstacles.  Great article here.  Now this is a jeep related article, but, the optimum psi principle remains the same for our rigs regardless.  


Edited by Advmoto18, 08 February 2019 - 05:20 PM.

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#35 Wallowa

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Posted 08 February 2019 - 05:38 PM

Phil

 

Actually, for off-road, lower air pressure vastly reduces the potential for tread punctures on modern tires due to tread conforming to obstacles.  Great article here.  Now this is a jeep related article, but, the optimum psi principle remains the same for our rigs regardless.  

  No belly bumping from me...your opinion is valid for you...

 

But higher pressures resist punctures by rolling over the object that could puncture the tire while low pressure conforms to the object and focuses the point of contact into the rubber... and higher pressure = less side wall flexing, and flexing generates higher tire temps that softens rubber which in turn makes the tire more prone to penetration...speed and load make flexing and heat more critical.

 

Again many mall pundits....read Scott and Sheppard...both have decades of off road experiences under extreme conditions....again take away what you wish but the internet is full of experts, at least so they say...

 

Phil


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#36 Advmoto18

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Posted 08 February 2019 - 09:55 PM

  No belly bumping from me...your opinion is valid for you...

 

But higher pressures resist punctures by rolling over the object that could puncture the tire while low pressure conforms to the object and focuses the point of contact into the rubber... and higher pressure = less side wall flexing, and flexing generates higher tire temps that softens rubber which in turn makes the tire more prone to penetration...speed and load make flexing and heat more critical.

 

Again many mall pundits....read Scott and Sheppard...both have decades of off road experiences under extreme conditions....again take away what you wish but the internet is full of experts, at least so they say...

 

Phil

 

Check!

Certainly no belly bumping from me intended or desired!

 

I've been part of the 4 wheeling and off-road jeep/truck scene since 1971.  Started out truck mud racing and finally got my fill jeep rock crawling in Uwharrie NF.

 

In all the decades, I have had 2 through the tread punctures as a result of rocks while off-road, both in the late 70s (that I can recall).  I don't recall the tire brand but most likely a Cepek as it was the "hot" tire to own back then.  I've damaged more than a few sidewalls but that was due to a bad line.  All the while running very low psi in the mud and rock.  And running about 15-20 psi during off-tarmac poker runs. 

 

Back in the 70s and 80s so called off-road tires were very heavy, stiff, and did not tolerate mistakes by the driver.  Modern, off-road radial tires are far more flexible and forgiving, and puncture resistant.  Yet, they still remain susceptible to damage if the driver isn't paying attention.

 

Incidentally, I've had far more flats as a result of hitting unseen debris and/or through the tread punctures on highways, operating at highway speeds and psi then in any other type of encounter.

 

So I totally agree, each to his own!  Find a psi that works for you given the terrain or road composition/condition.

 

Cheers!


Edited by Advmoto18, 08 February 2019 - 10:00 PM.

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#37 rubberlegs

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Posted 09 February 2019 - 06:34 AM

 

Another interesting article. With our truck (Tacoma) with front axle 2800, rear axle 3460 lbs:

 

Stock P tires: street pressure 35/43 psi, can go down to 12/15 psi for off road. (compare to 30/40 for another method).

 

LT tires: street pressure 42/52 psi, can go down to 15/18 psi rear (compare to 42/56).


Edited by rubberlegs, 09 February 2019 - 06:36 AM.

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