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Old 06-23-2016, 12:01 PM   #15
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Originally Posted by bobcovey View Post
You caught my attention with that statement because I thought that I had done my homework on tires and inflation. So, I went back to Goodyear, specifically: https://www.goodyeartrucktires.com/p...dinflation.pdf
Nowhere in this document do I see what you claim. Quite the opposite; Goodyear provides a calculation chart to help determine precise pressures for load and speeds.
The placard air pressures in my coach are for GVWR, not actual weights, and only valid for the OEM tires, coincidentally Goodyear G670s. They are not accurate for actual weights and other brands of tires.
I will stand by what I recommended to Dave: weigh the coach and adjust per the charts. 4 corner weighing is certainly preferable, but axle weights are better than guessing. I did forget to add that like Jim I also add 5 psi.
I recently replaced the G670s with Toyo M144A tires. The Toyos do ride and handle better than the Goodyears, but those differences would not have justified the cost, at least to me. I needed new tires and picked the Toyos based on cost, reputation and availability when I decided to write the check.

Cheers,
I recall having read the same statement about tire manufactures recomendation to never go below the RV builders inflation Tag.

Try looking at a more recent Goodyear tire guide, you may see it.
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Old 06-23-2016, 02:44 PM   #16
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Quote:
Originally Posted by twinboat View Post
I recall having read the same statement about tire manufactures recomendation to never go below the RV builders inflation Tag.

Try looking at a more recent Goodyear tire guide, you may see it.
I believe that the tire manufacturer is trying to throw blame on the RV builder if they indeed made that statement. I have spoken with veteran tire experts and they would never make a statement like that. The reason being they know the RV builder has no control over how the OWNER will use (or misuse) the motorhome. They will tell you that they know the limitations of the tire and how the tire should be used so they will tell you - weigh the motor home in travel configuration and inflate based on that weight.
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Old 06-23-2016, 07:03 PM   #17
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When I questioned the confusion between minimum and maximum pressures that so many profess to understand, I contacted a Michelin rep for his interpretation. He said that the pressures recommended for any weight less that the maximum rated load capacity "Is" the minimum psi for that load. However, when the load reaches the maximum rated load, the minimum psi becomes the maximum cold psi for the tire. On my 295X80/22.5 tires I think the maximum load rating is 7860# and the minimum psi is 120#. That is also the maximum "cold" pressure for the tire.
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Old 06-23-2016, 11:08 PM   #18
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Originally Posted by twinboat View Post
I recall having read the same statement about tire manufactures recomendation to never go below the RV builders inflation Tag.

Try looking at a more recent Goodyear tire guide, you may see it.
That IS the current link from https://www.goodyeartrucktires.com. As far as I am concerned, that is Goodyear's position on this topic. Toyo's inflation guidelines essentially mirror it. Absent documentation to the contrary, I don't see any reason to change my recommendation to Dave.
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Old 06-23-2016, 11:12 PM   #19
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Originally Posted by Ron_H View Post
The PSI number on the tire sidewall is the "Maximum" pressure for the tire to carry its maximum weight.
The pressure on the sidewall of a Michelin RV truck size tire and many others is not the "Maximum" the tire should ever have (unlike car tires) it is the minimum to support the maximum rated carrying capacity of the tire. NHTSA defines a truck tire as those used on anything with a GVWR of 10,000#'s or more.

From the Michelin RV Tire Guide:
Quote:
"If you look at the tire's sidewall, you'll see the maximum load capacity allowed for the size tire and load rating, and the minimum cold air inflation needed to carry the maximum load."
From page 6 of the GoodYear RV Tire and Care Guide:
Quote:
"How much air is enough?
The proper air inflation for your tires depends on how much your fully loaded RV or trailer weighs. Look at the sidewall of your RV tire and you’ll see the maximum load capacity for the tire size and load rating, as well as the minimum cold air inflation, needed to carry that maximum load."
From TOYO:
Quote:
Q: What are the consequences of inflating the tires to accommodate the actual loads?
A: If the inflation pressure corresponds to the actual tire load according to the tire manufacturer’s load and pressure table, the tire will be running at 100% of its rated load at that pressure. This practice may not provide sufficient safety margin. Any air pressure loss below the minimum required to carry the load can result in eventual tire failure.
But then they go ahead and publish a weight/pressure chart allowing lower pressure for RV's!!

From the August 2010 Motorhome Magazine "Tread Carefully" tire article:
Quote:
The maximum load capacity allowed for the size tire and load rating and the minimum cold air inflation needed to carry that maximum load are located on the tire’s sidewall.
From our owners manual:
Quote:
Federal law requires that the tire’s maximum load rating be molded into the sidewall of the tire.
If you look there, you will see the maximum load allowed and the cold air inflation pressure required to carry that stated maximum load. Less air pressure restricts the tire to carry a lighter load.
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Old 06-24-2016, 06:28 AM   #20
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Originally Posted by bobcovey View Post
That IS the current link from https://www.goodyeartrucktires.com. As far as I am concerned, that is Goodyear's position on this topic. Toyo's inflation guidelines essentially mirror it. Absent documentation to the contrary, I don't see any reason to change my recommendation to Dave.
I have no problem with your position but you supplied a 2010 link.

I am referring to a 2014 link.

rv_inflation_guide_nov112014
Attached Files
File Type: pdf rv_inflation_guide_nov112014.pdf (721.1 KB, 25 views)
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