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 > PSI of LT tire after upgrading from P rated tire

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CALandLIN

SC

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Posted: 05/26/20 03:39pm Link  |  Quote  |  Print  |  Notify Moderator

I haven’t seen the correct procedure yet so I’m going to write the way it’s supposed to be done.

First, the replacement tires are required to provide a load capacity equal to or greater than what the OE tires provided as indicated by the certified recommended cold inflation pressures for them, depicted on the vehicle certification label.

Second, the vehicle manufacturer already accounted for the 10% decrease in load capacity for “P” tires with their recommended cold inflation pressures for the OE tires.

Third, you’ll need a load inflation chart for the replacement tires. With it you can set new recommend cold inflation pressures for the replacement tires with an inflation pressure that will meet the minimum requirements. Anything above your new recommended cold inflation pressures is optional all the way to tire sidewall max.

JIMNLIN

Oklahoma

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Posted: 05/26/20 08:09pm Link  |  Quote  |  Print  |  Notify Moderator

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This information is actually uniform across all tires so we do not have our own chart. I did google it for you though and found this link: http://www.yournexttire.com/trailer-load-inflation-chart/.

The chart is always a good place to start. From there you can fine tune psi that gives you the best ride....best handling and best long term tire wear for a empty truck and a fully loaded truck.


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mowermech

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Posted: 05/27/20 05:57am Link  |  Quote  |  Print  |  Notify Moderator

Years back, I had a Jeep Wrangler Rubicon Unlimited that came from the factory with LT Load Range E tires. Recommended inflation pressure, according to the door jamb sticker? 33 PSI! No way would I ever be crazy enough to inflate to the 80 PSI pressure stated on the sidewall for Max Load!
I made several trips of 1500 miles or more, at 70 MPH in that Jeep. Never had a tire problem.
I spent some time off-roading that Jeep at 5 MPH (or less), with the tires deflated to 12 PSI. No tire problems.
When I bought new tires for the rear of the motorhome, Load Range F tires were not available, I had to buy Load Range G. I told the tire guy to inflate to the LR F specs on the data plate. He argued, but eventually did it my way. No tire problems. They are about to age-out, so I will have to replace them soon. I'm sure we will have the same argument, and he will do it my way again.
I find it interesting that after all the mental gymnastics and number crunching, the OP came up with the same tire pressure as that stated on the data plate, or perhaps a little more, depending on the source. I certainly got a chuckle out of the 80% of rated pressure for LT tires, when Jeep recommended 33 PSI for LT LR E on the Wrangler Rubicon!
Oh, well, it was on the internet, so it MUST be correct, right?

* This post was edited 05/27/20 06:04am by mowermech *


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CapriRacer

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Posted: 05/27/20 06:39am Link  |  Quote  |  Print  |  Notify Moderator

JIMNLIN wrote:

Quote:

This information is actually uniform across all tires so we do not have our own chart. I did google it for you though and found this link: http://www.yournexttire.com/trailer-load-inflation-chart/.

The chart is always a good place to start. From there you can fine tune psi that gives you the best ride....best handling and best long term tire wear for a empty truck and a fully loaded truck.


CAUTION: That chart is for ST type tires - and this thread is in "Tow Vehicles"!!


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cj_rezz

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Posted: 06/07/20 11:12pm Link  |  Quote  |  Print  |  Notify Moderator

CapriRacer wrote:

JIMNLIN wrote:

Quote:

This information is actually uniform across all tires so we do not have our own chart. I did google it for you though and found this link: http://www.yournexttire.com/trailer-load-inflation-chart/.

The chart is always a good place to start. From there you can fine tune psi that gives you the best ride....best handling and best long term tire wear for a empty truck and a fully loaded truck.


CAUTION: That chart is for ST type tires - and this thread is in "Tow Vehicles"!!


Geez, I didn't even look at the chart they linked to; I just assumed it was a standard chart that I was referencing earlier. They totally linked to the wrong chart!


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StirCrazy

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Posted: 06/08/20 08:05am Link  |  Quote  |  Print  |  Notify Moderator

cj_rezz wrote:

StirCrazy wrote:

are you using a generic table for your tire PSI/Load , do your self a favor and email the manufacture and ask for the load chart for that tire.

I did this for mine, the values are close but they also can give you little tips that are specific for that tire. for mine they recommended not to run the tire under 50psi as at 45PSI they get inconsistent wear.

Steve


I am just using generic tables at this point. I did email Nokian a couple of days ago but haven't heard anything back yet. Hopefully I will and this will provide some extra information.


ya the numbers will be pretty close, but if I went for the unloaded weight on my tires, i would be running them at about 35 PSI. but the company said not to run them under 45 so I picked 50 for my unloaded rear PSI to give a bit of room. when I am loaded with the 5th wheel I run 75 PSI, got 80000Km out of the last set doing this so must be good. for loaded I set the tires at 5PSI above the PSI for my actual weight on the chart for the rear.

Steve


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Grit dog

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Posted: 06/08/20 04:19pm Link  |  Quote  |  Print  |  Notify Moderator

StirCrazy wrote:


ya the numbers will be pretty close, but if I went for the unloaded weight on my tires, i would be running them at about 35 PSI. but the company said not to run them under 45 so I picked 50 for my unloaded rear PSI to give a bit of room. when I am loaded with the 5th wheel I run 75 PSI, got 80000Km out of the last set doing this so must be good. for loaded I set the tires at 5PSI above the PSI for my actual weight on the chart for the rear.

Steve


All good, but curious what tires and what "company" said 45psi min?
Doesn't make sense. 19.5s need considerably more and I haven't ever seen a LRE tire that was 45psi min.


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