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Old 04-12-2016, 09:47 PM   #15
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Most folks dont run down the road loaded down to the maximum capacity of their rig. That being said, you will likely never run your tires at the minimum cold pressure for the maximum capacity of the tire. Weigh your coach and then consult your tire manufacturers inflation chart. Although my tires are rated at 105 cold, I run as low as 75 pounds in them. Running at 105 with a light load would most likely result in my coach coming apart and my fillings most definitely coming out of my teeth.
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Old 04-12-2016, 09:53 PM   #16
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Informative Thanks!

Good information. I had just checked and topped off my tires at the max 110 which not only is on the tires but also on the placard by the drivers seat and these tires are not the same brand that came with the coach. I wondered why the TP would be on the placard since brands are all different but then just guessed this must be a industry standard.

All my years of driving commercial motorcoaches and also buses for the school district, we do a pre-trip check on tires by hitting them with a tire baton and if it feels "right" sign it off. If it feels "odd" take it to maintenance.

I know these suckers are costly. I think the FMCA Michelin Advantage program might be a good investment.

James
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Old 04-12-2016, 11:04 PM   #17
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Weigh your coach and run your tires at the weight/pressure chart plus 5 to 10 percent, whatever makes you comfy. DO NOT run them underinflated and no one cares how rough the ride might be. Running underinflated tires usually leads to threads here titled "RVers die in crash, blowout to blame." and the like.

Don't guess, don't follow someone else's pressure; weigh it and follow the manufacturers chart.

FWIW by the chart I'm 110 rear and 105 front; sticker and placards say 95...but the fact is those 1993 tires were overloaded.
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Old 04-13-2016, 11:49 PM   #18
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Get ready for travel, full fuel, full water (Even if you normally travel with less.), does not hurt to have some Grey/Black on board too.). Get a four corner weight, with individual scales being the best way to do this. Consult the Tire Manufactures PSI chart, add your safety contingency to this (I now run 10% above.). Set your tire PSI, adjusting up/down for outside temps at that time. Correlate the tire PSI to your Tire Monitoring System reported PSI. Then go travel. At the start, and during stops, do a walk around visual of your rig, including looking for tire problems.

Then go travel... and have a blast,
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Old 04-13-2016, 11:59 PM   #19
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Originally Posted by Kro1957 View Post
Good information. I had just checked and topped off my tires at the max 110 which not only is on the tires but also on the placard by the drivers seat and these tires are not the same brand that came with the coach. I wondered why the TP would be on the placard since brands are all different but then just guessed this must be a industry standard.

All my years of driving commercial motorcoaches and also buses for the school district, we do a pre-trip check on tires by hitting them with a tire baton and if it feels "right" sign it off. If it feels "odd" take it to maintenance.

I know these suckers are costly. I think the FMCA Michelin Advantage program might be a good investment.

James
Again, the pressure on the tire sidewall of RV tires is NOT the maximum cold pressure the tire should ever have. It is the MINIMUM to support the maximum rating of the tire.
Also, a trucker magazine did a test with 50 professional drivers and found the only 2 of them could accurately tell a tire that was 20% low in pressure and 20% low is the pressure at which tire damage can occur.
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Old 04-14-2016, 06:08 AM   #20
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Again, the pressure on the tire sidewall of RV tires is NOT the maximum cold pressure the tire should ever have. It is the MINIMUM to support the maximum rating of the tire.
Mr D-

A question for you: Are there cases where you (or the manufacturers) would recommend inflating a tire over the marked tire sidewall pressure?

If not, I suggest that the definition you've provided is a statement that a tire is designed with an above-the-sidewall-marked inflation safety margin, which I think is something most everyone assumes is the case.
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Old 04-14-2016, 06:28 AM   #21
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Mr D-

A question for you: Are there cases where you (or the manufacturers) would recommend inflating a tire over the marked tire sidewall pressure?

If not, I suggest that the definition you've provided is a statement that a tire is designed with an above-the-sidewall-marked inflation safety margin, which I think is something most everyone assumes is the case.
I did some digging on that exact statement a while back and found that over inflating by, I think 10%, was approved for heavy loading and slow speed use. Not MHs traveling down the highway.
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Old 04-15-2016, 09:37 PM   #22
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Misinformation or Semantics?

Quote:
Originally Posted by XXXXX
Again, the pressure on the tire sidewall of RV tires is NOT the maximum cold pressure the tire should ever have. It is the MINIMUM to support the maximum rating of the tire.

Let's all go to the source, and review what these markings actually mean.

Tire Safety, Brochure (DOT HS 809 361 October 2001)
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Old 04-16-2016, 01:25 PM   #23
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In my post from 2013 I already gave the difference between , I will call it AT-pressure , and maximum cold pressure.

But again, I PDF of Semperit /Continental maximum cold pressure is given as 1.4 times AT-pressure.
But also American makers like Goodyear alow 10 psi extra above AT for LT tires and gave 20 psi extra for Truck-tires , but in newer documents also 10 psi above AT. They advice it for higher speed and better road handling for ST tires.
But you are allowed to drive only 50 m/h with this pressure .

Michelin and Continental have in Europe 8PR/D-load tires especially for motorhomes called special camper, XC, Vancocamper, wich have AT pressure of 70 psi and give maximum pressure on sidewall of 80 psi ( that 10 psi extra)
Michelin only gives that 80 psi max , but Continental gives both max cold and At pressure on sidewall.

I once read from Tireman 9 or Capricacer, that tires are tested to can stand a pressure of 2 to 3 times AT-pressure , so cold or warm.
This means that a E load tire with AT pressure of 80 psi can stand a pressure of 160 to 240 psi before it blows.
If you would fill such a tire at freesing point of water so 32 degr F with 1.4 times 80 psi is 112 psi , and temp rises in tire to 212 degr F so boiling point of water, the pressure would rise to 159 psi wich is almost 2 times the AT pressure of 80 psi.

Risk is that the tiremaker designed a tire for D-load with AT pressure of 65 psi , but after testing sets it in the market as E-load . Then the tire can stand a pressure of 130 to 195 psi max ( 2 to 3 times 65) and the 159 psi is still save.
If then 10 psi extra is only allowed by tiremaker then 80 + 10 =90 psi cold filled at 32 degr F becomes 129 psi at 212 degr F so below 2+65 =130 psi.

Mayby thats the reason for the different extra pressure allowed cold between Europe and America.
In Europe its hard to find a E-load tire , and in America E-load tires are found easyly.

Also valves are tested to can stand a higher pressure then they are given as max for cold pressure, so a valve importer in Holland ( where I live) made me wiser.
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Old 04-16-2016, 06:14 PM   #24
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Again, the pressure on the tire sidewall of RV tires is NOT the maximum cold pressure the tire should ever have. It is the MINIMUM to support the maximum rating of the tire.
Mr D, you keep quoting that without any indication of what you mean by it, and how it can be applied in the real world where the tyre manufacturers would much prefer that we weighed the coach and made proper use of the manufacturers load/inflation tables. Anyone forced to run tyres at these cold presures should give some thought to fitting a higher rated tyre.

Anyone who blithely pumps tyres up to the rated cold inflation pressure regardless of the load is doing the tyres, coach and the passengers a great disservice.
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Old 04-16-2016, 06:27 PM   #25
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Mr D, you keep quoting that without any indication of what you mean by it, and how it can be applied in the real world where the tire manufacturers would much prefer that we weighed the coach and made proper use of the manufacturers load/inflation tables. Anyone forced to run tires at these cold pressures should give some thought to fitting a higher rated tire.

Anyone who blithely pumps tires up to the rated cold inflation pressure regardless of the load is doing the tyres, coach and the passengers a great disservice.
I'm posting DIRECT QUOTES from the tire manufacturers and magazine articles that all say the same thing. I hope people are cognizant enough to figure out that what the posts say.
Anyone is free to look up the info since I also post where the cite comes from.
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Old 04-16-2016, 06:31 PM   #26
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Let's all go to the source, and review what these markings actually mean.

Tire Safety, Brochure (DOT HS 809 361 October 2001)
Good info for CAR tires, but no where in there does it say anything about any tires larger then LT. Whereas the info I post, and will continue to post, is specifically for truck size RV tires for vehicles weighing over 10,000#'s
Quote:
AGENCY: National Highway Traffic Safety Administration (NHTSA), Department of Transportation.
ACTION: Final Rule.
SUMMARY: In response to the Transportation Recall Enhancement, Accountability, and Documentation (TREAD) Act of 2000, this document establishes a new Federal Motor Vehicle Safety Standard to improve the information readily available to consumers about tires.�The new information will assist consumers in identifying tires that may be the subject of a safety recall.�It will also increase public awareness of the importance and methods of observing motor vehicle tire load limits and maintaining proper tire inflation levels for the safe operation of a motor vehicle. This rule applies to all new and retreaded tires for use on vehicles manufactured after 1975 with a gross vehicle weight rating of 10,000 pounds or less and to all new vehicles with a gross vehicle weight rating of 10,000 pounds or less, except for motorcycles and low speed vehicles.�
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Old 04-17-2016, 02:13 AM   #27
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Good info for CAR tires, but no where in there does it say anything about any tires larger then LT. Whereas the info I post, and will continue to post, is specifically for truck size RV tires for vehicles weighing over 10,000#'s
I suggest you read FMVSS 571.120.
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Old 04-17-2016, 03:49 PM   #28
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Semantics, cont'd

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I suggest you read FMVSS 571.120.
Specifically, Paragraph S6.5 Tire markings. Sub-paragraph (d)

"(d) The maximum load rating and corresponding inflation pressure of the tire, shown as follows..."

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