Tire pressure help

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Originally Posted by Env1ous

This is the run around I got on other forums while asking. I liked the chart and info you provided. I knew there had to be a science behind it that made more sense.



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Originally Posted by OVERKILL
IIRC, the "proper" method for determining pressure is to use the load tables.

If you go to the load tables and see that your factory P-rated tires which were, for the sake of this example, 275/60R18s and spec'd 35psi, which results in a load rating of 2,403lbs, we then need to de-rate them by 10% to account for a P-rated tire on a truck/SUV, which results in a 2,185lb rating.

So, you look at the load table for the LT tires, which is, for your size, down on page 23, and we see that for a 275/70R18 we need 40PSI to achieve roughly the same weight rating.

So, find your factory tires in the P-metric list, find their weight rating, derate them by 10%, and that will give you the the minimum value you need to shoot for when choosing a pressure for the LT tires.
THE ONE ABSOLUTELY CORRECT ANSWER ... why don't the sheeple accept it.
 
Originally Posted by George Bynum
THE ONE ABSOLUTELY CORRECT ANSWER ... why don't the sheeple accept it.


That's why they are sheeple...
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Guys,is it so difficult to differentiate between :
a)a sub-system in an E range tire comprising air system, which is designed and manufactured for 80 psi max , vs
b)a complete-system comprising tire sub-system AND vehicle weights/power/torque, AND passenger(s) etc etc , whereby OP selects/prefers/decides on whatever 4x psi ?

Aren't you a sheeple incapable of making differentiation between (a) and (b) above ?
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Edit:Read 'Systems Engineering' .
 
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Originally Posted by MParr
Just a reminder; a load range E tire is standard for 3/4 ton trucks. With a 3/4 ton truck tire, it's going to be a a harder ride. Fill to the pressure on the door sticker.

Originally Posted by MParr
Just a reminder; a load range E tire is standard for 3/4 ton trucks. With a 3/4 ton truck tire, it's going to be a a harder ride. Fill to the pressure on the door sticker.

Originally Posted by MParr
Just a reminder; a load range E tire is standard for 3/4 ton trucks. With a 3/4 ton truck tire, it's going to be a a harder ride. Fill to the pressure on the door sticker.

Originally Posted by MParr
Just a reminder; a load range E tire is standard for 3/4 ton trucks. With a 3/4 ton truck tire, it's going to be a a harder ride. Fill to the pressure on the door sticker.

I agree. Go with the pressure on the door sticker. When I had a pickup and the bed was empty I filled the rear tires same as the front. The few times I had a substantial load in the bed I jacked up the pressure.
 
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Originally Posted by das_peikko
I am going to email my reliable source and see what he says about the 80 PSI tire.


Your advice runs contrary to the advice of the tire engineer on this board. That's right, a guy who engineers tires has weighed in on this topic dozens of times, and you don't want to accept what he says, or what other folks say, sticking to your "x less than sidewall" advice that is in error.

Your "reliable source" is irrelevant, because he has nowhere near the experience of the engineer, whose advice can be found on the link that Overkill provided:

http://barrystiretech.com/
 
Originally Posted by Astro14
Originally Posted by das_peikko
I am going to email my reliable source and see what he says about the 80 PSI tire.


Your advice runs contrary to the advice of the tire engineer on this board. That's right, a guy who engineers tires has weighed in on this topic dozens of times, and you don't want to accept what he says, or what other folks say, sticking to your "x less than sidewall" advice that is in error.

Your "reliable source" is irrelevant, because he has nowhere near the experience of the engineer, whose advice can be found on the link that Overkill provided:

http://barrystiretech.com/

.... ignoring the FACT that an E range tire is designed , manufactured and spec'ed for MAX 80 psi inflation pressue ?

Tire specification aside , selection of inflation pressure is influenced by other factors in specific application.
Das selects "4 PSI below the maximum on the tire" .
OP selects 45 psi.
Both selections (of 76 psi and 45 psi) are in full compliance of "MAX 80 psi' specifications.

In simple layman terms,tire manufacturers guarantee E range tires as FIT for max 80 psi.This parameter is BACKED by all tire manufacturers, and tire standards organisation .


Edit:grammar
 
Last edited:
Originally Posted by zeng

.... ignoring the FACT that an E range tire is designed , manufactured and spec'ed for MAX 80 psi inflation pressue ?

Tire specification aside , selection of inflation pressure is influenced by other factors in specific application.
Das selects "4 PSI below the maximum on the tire" .
OP selects 45 psi.
Both selections (of 76 psi and 45 psi) are in full compliance of "MAX 80 psi' specifications.

In simple layman terms,tire manufacturers guarantee E range tires as FIT for max 80 psi.This parameter is BACKED by all tire manufacturers, and tire standards organisation .


Edit:grammar


Right up there with the dumbest things I've ever read about tire pressure
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Last edited:
Originally Posted by gaijinnv
Originally Posted by zeng

.... ignoring the FACT that an E range tire is designed , manufactured and spec'ed for MAX 80 psi inflation pressue ?

Tire specification aside , selection of inflation pressure is influenced by other factors in specific application.
Das selects "4 PSI below the maximum on the tire" .
OP selects 45 psi.
Both selections (of 76 psi and 45 psi) are in full compliance of "MAX 80 psi' specifications.

In simple layman terms,tire manufacturers guarantee E range tires as FIT for max 80 psi.This parameter is BACKED by all tire manufacturers, and tire standards organisation .


Edit:grammar


Right up there with the dumbest things I've ever read about tire pressure
33.gif



Please explain with facts, in Physics of tires if you aren't another sheeple ?
 
Originally Posted by zeng
Originally Posted by gaijinnv
Originally Posted by zeng

.... ignoring the FACT that an E range tire is designed , manufactured and spec'ed for MAX 80 psi inflation pressue ?

Tire specification aside , selection of inflation pressure is influenced by other factors in specific application.
Das selects "4 PSI below the maximum on the tire" .
OP selects 45 psi.
Both selections (of 76 psi and 45 psi) are in full compliance of "MAX 80 psi' specifications.

In simple layman terms,tire manufacturers guarantee E range tires as FIT for max 80 psi.This parameter is BACKED by all tire manufacturers, and tire standards organisation .


Edit:grammar


Right up there with the dumbest things I've ever read about tire pressure
33.gif



Please explain with facts, in Physics of tires if you aren't another sheeple ?


Eloquently, completely, and professionally explained, with details and facts, in the link I provided.

Your failure to read that link, to examine facts, original sources and professional analysis, ensures your continued sheeple membership.
 
Originally Posted by US Tire Manufacturers Association
NOTE: The pressure indicated on the tire sidewall is the maximum allowed in the tire, irrespective of the vehicle. Follow the vehicle manufacturer's recommendations for inflation pressure found on the vehicle tire placard, certification label or in the owner's manual.


Excerpt from the USTMA publication Care and Service of Passenger and Light Truck Tires, page 11.

Care and Service of Passenger and Light Truck Tires
 
Originally Posted by zeng
Originally Posted by gaijinnv
Originally Posted by zeng

.... ignoring the FACT that an E range tire is designed , manufactured and spec'ed for MAX 80 psi inflation pressue ?

Tire specification aside , selection of inflation pressure is influenced by other factors in specific application.
Das selects "4 PSI below the maximum on the tire" .
OP selects 45 psi.
Both selections (of 76 psi and 45 psi) are in full compliance of "MAX 80 psi' specifications.

In simple layman terms,tire manufacturers guarantee E range tires as FIT for max 80 psi.This parameter is BACKED by all tire manufacturers, and tire standards organisation .


Edit:grammar


Right up there with the dumbest things I've ever read about tire pressure
33.gif



Please explain with facts, in Physics of tires if you aren't another sheeple ?


The OP wanted help in determining the proper Cold Tire Inflation Pressure for his truck when he went from a stock P-Metric tire to an alternative LT-Metric tire. This is a common question that has been addressed repeatedly by the tire industry.

Even though you probably won't even read it, I offer the following link for an eassy to understand explanation of the process for answering the OP's question (start on page 11, the section "P-Metric to LT-Metric"): Guidelines for the Application of Load and Inflation Tables

Your ridiculous assertions of "in compliance" and "fit" are just made-up pseudo-science with no basis in practice - unless, of course, you are the sheeple.

HTH
 
My reliable source says 65 PSI with the truck empty and 75 PSI with the truck loaded down.

You guys need to remember that these are 10 ply tires. Not your average passenger car tire.

They were not meant for a soft ride from the get-go.
 
Originally Posted by das_peikko
My reliable source says 65 PSI with the truck empty and 75 PSI with the truck loaded down.

You guys need to remember that these are 10 ply tires. Not your average passenger car tire.

They were not meant for a soft ride from the get-go.


Apparently you need to be reminded that it doesn't matter if these are 30-ply tires, they are going on a 1/2 ton that originally was fitted with P-Metric tires. He only needs to match the load carrying capacity of the OEM tires, which occurs at far less than 65psi (45psi actually).
 
Originally Posted by das_peikko
My reliable source says 65 PSI with the truck empty and 75 PSI with the truck loaded down.

You guys need to remember that these are 10 ply tires. Not your average passenger car tire.

They were not meant for a soft ride from the get-go.


Your "reliable source" has just proven to be... unreliable.

That tire pressure recommenation is dangerously overinflated, unsafe and irresponsible.

By extension, you have also proven yourself to be... unreliable.

So noted.

HTH
 
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Originally Posted by das_peikko
…… Also look at the difference in weight of the tires because of the amount of steel belts. 10 ply vs. 4 ply.


Ah … Mmmm ….. I'm going to suggest that you quit while you're behind. That last statement shows you don't know much about Load Range E tires. They don't have 10 plies and there are only 2 steel belts in them - same as the P metrics. (IF you want to know the correct answer, look at the sidewall of a LR E tire.)
 
Originally Posted by das_peikko
It's because of the load range the tire was built for.

https://tiresize.com/tires/Cooper/Discoverer-ATP-275-70R18.htm
(Load Range Classification E) - 3640 Pounds Max - 80 PSI @ Max Load

https://tiresize.com/tires/Cooper/Discoverer-SRX-275-65R18.htm
(Load Range Classification Standard) - 2656 Pounds Max - 44 PSI @ Max Load

Also look at the difference in weight of the tires because of the amount of steel belts. 10 ply vs. 4 ply.


This is still going right over your head.

You know why they call it a load RANGE? Think about it until you do.

Vehicles that actually spec E-rated tires often don't call for anywhere near 80psi. Why? The reason is that the load carrying capacity needed isn't anywhere near what is provided at 80psi. This is why there are load tables. A tire's performance in other metrics beyond simple carrying capacity change with pressure. The OEM's use the load tables to determine what pressure is needed for an application and then fine tune above that for the best balance of ride, handling, steering feedback, traction...etc.

The reason my old F-250 called for 55psi in load range E tires on the front axle is the same reason the OP's F-150 (half ton truck) requires only 45psi. That's where the sufficient load carrying capacity of the tire's load RANGE aligns.

Maximum pressure/sidewall is not a recommendation. It's an indication of the pressure required to obtain the maximum load carrying capacity of the tire. This is why one goes by the placard, which is actually the tested-for and determined appropriate pressure for the vehicle. In the OP's case, because he's deviated from the stock P-Metric tires, the appropriate course of action is to back-track how the manufacturer arrived at the pressure spec they did, which he's done, using the load tables, and then cross that over to the tires he has fitted to ensure they align. This results in an inflation pressure of 45psi.
 
Originally Posted by gaijinnv
Originally Posted by zeng
Originally Posted by gaijinnv
Originally Posted by zeng

.... ignoring the FACT that an E range tire is designed , manufactured and spec'ed for MAX 80 psi inflation pressue ?

Tire specification aside , selection of inflation pressure is influenced by other factors in specific application.
Das selects "4 PSI below the maximum on the tire" .
OP selects 45 psi.
Both selections (of 76 psi and 45 psi) are in full compliance of "MAX 80 psi' specifications.

In simple layman terms,tire manufacturers guarantee E range tires as FIT for max 80 psi.This parameter is BACKED by all tire manufacturers, and tire standards organisation .


Edit:grammar


Right up there with the dumbest things I've ever read about tire pressure
33.gif



Please explain with facts, in Physics of tires if you aren't another sheeple ?


The OP wanted help in determining the proper Cold Tire Inflation Pressure for his truck when he went from a stock P-Metric tire to an alternative LT-Metric tire. This is a common question that has been addressed repeatedly by the tire industry.

Even though you probably won't even read it, I offer the following link for an eassy to understand explanation of the process for answering the OP's question (start on page 11, the section "P-Metric to LT-Metric"): Guidelines for the Application of Load and Inflation Tables

Your ridiculous assertions of "in compliance" and "fit" are just made-up pseudo-science with no basis in practice - unless, of course, you are the sheeple.

HTH


This is what helped me out. I figured I needed 45PSI and wow it made a huge difference. I went from 50PSI down to 45 and I am very happy. Even the wife said she noticed a huge difference.
 
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