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Old 06-04-2020, 11:49 AM   #81
Tireman9
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Originally Posted by CWtheMan View Post
That is mostly true, as long as you don't violate safety standards.

Basic, allowable modifications, are defined in the vehicle certification regulation.

Precedents cannot be overlooked because they form the basis for all future actions. It's one of the reasons I referenced the "Vehicle In Use Inspection Standards" regulation. It's not binding unless it's applied. However, it provides minimum compliance actions once applied.

A simple example: A consumer is replacing all their tires on an RV trailer. The OE size depicted on the vehicle certification label is ST225/75R15 and the vehicle manufacturer's recommended cold inflation pressure for all of those tires is certified at 65 PSI which sets the minimum load capacity for any subsequent/replacement tires. The consumer want's a little more load capacity reserves from the replacement tires and has higher load capacity tires installed as replacements. IF the replacement tires have a designated size of ST225/75R15 and will provide an equal or greater load capacity than the OE tires, there is zero size upgrade. Just tires of the same basic size as the OE tires with a little more load capacity. Load Range is not part of a tire's designated size.

A reader of government regulations must first determine who the regulations are addressing. For instance, the FMVSS (standards) are mandatory minimum compliance standards the vehicle manufacturer MUST comply with.

One of the most widely misunderstood FMVSS standard is about tire load capacity. The standard says tires fitted to RV trailer axles must provide a load capacity equal to vehicle certified GAWR (s). That statement is not directed at the consumer. It's sets the starting point for vehicle manufacturers selection for tires they deem appropriate for that vehicle. Once they select and fit the OE designated tire size and recommended cold inflation pressures they become the minimum standard for that vehicle. That information is then placed on the vehicle certification label.

Safety standards are one sided. Stating a MINIMUM load capacity or a MAXIMUM level of loading.


For tires it is a MINIMUM load capacity that should be meet or exceeded. For something like a ladder that says "MAXIMUM allowable load of 250# means there should be no greater load applied.
I have never heard of any Safety standard that prevented doing something that was more safe than the requirement. If there is such can you provide the reference.
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Old 06-04-2020, 01:04 PM   #82
CWtheMan
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Originally Posted by Tireman9 View Post
Safety standards are one sided. Stating a MINIMUM load capacity or a MAXIMUM level of loading.


For tires it is a MINIMUM load capacity that should be meet or exceeded. For something like a ladder that says "MAXIMUM allowable load of 250# means there should be no greater load applied.
I have never heard of any Safety standard that prevented doing something that was more safe than the requirement. If there is such can you provide the reference.
You seem to be baiting. What is a standard? For original equipment tires the vehicle manufacturer set a minimum standard. Why, you might ask? Because the selection standard told the vehicle manufacturer how low they could go and to insure the OE tires are appropriate for that fitment. NHTSA mandated that standard with this quote; "Tire Size, To maintain tire safety, purchase new tires that are the same size as the vehicle’s original tires or another size
recommended by the manufacturer. Look at the Tire and Loading Information label, or the sidewall of the tire you are replacing to find this information. If you have any doubt about the correct size to choose, consult with the tire
dealer."

You and I both know that "tire size" is officially "designated tire size" and the FMVSS states it that way in 571.110 & 571.120.
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Old 06-04-2020, 01:35 PM   #83
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Absolutely. Old tires were e rated 10 Ply with a weight capacity of 2,860. New tires are also 10 Ply e rated and have a weight capacity of 3,420 lbs. Wheels are 16 steel dexstar with a weight capacity of 3,050 My fifth wheel has dual 5,200 lb axles and has a gross vehicle weight rating of 11,500 lbs.





Thanks. The "Reserve Load" I would like to calculate is


GAWR as stated on vehicle Tire Placard (AKA Certification label




(tire load capacity at placard inflation) - (GAWR) = Reserve Load


The Reserve Load is often stated as the absolute number of pounds but sometimes a percentage is more meaningful when looking at a variety of different vehicles.



Grose vehicle rating is not simply GAWR x 2
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Old 06-04-2020, 01:41 PM   #84
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Originally Posted by CWtheMan View Post
You seem to be baiting. What is a standard? For original equipment tires the vehicle manufacturer set a minimum standard. Why, you might ask? Because the selection standard told the vehicle manufacturer how low they could go and to insure the OE tires are appropriate for that fitment. NHTSA mandated that standard with this quote; "Tire Size, To maintain tire safety, purchase new tires that are the same size as the vehicle’s original tires or another size
recommended by the manufacturer. Look at the Tire and Loading Information label, or the sidewall of the tire you are replacing to find this information. If you have any doubt about the correct size to choose, consult with the tire
dealer."

You and I both know that "tire size" is officially "designated tire size" and the FMVSS states it that way in 571.110 & 571.120.



Sorry, no "baiting" intended. I am interested in learning Reserve Load on various RV trailers as I have found numbers for vehicle Reserve Load from a negative 2% to as high as +40% on some motor vehicles. RV trailers tend to run below 10% assuming the GAWR has not been exceeded AND that the tire is fully inflated to Placard. But we both know that in the real world a majority of thousands of RVs that have been weighed have discovered one or more tire and/or axle is in overload.


RE the -2% yes I filed a complaint with NHTSA on that one.
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Old 06-05-2020, 01:02 PM   #85
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Originally Posted by Tireman9 View Post
Sorry, no "baiting" intended. I am interested in learning Reserve Load on various RV trailers as I have found numbers for vehicle Reserve Load from a negative 2% to as high as +40% on some motor vehicles. RV trailers tend to run below 10% assuming the GAWR has not been exceeded AND that the tire is fully inflated to Placard. But we both know that in the real world a majority of thousands of RVs that have been weighed have discovered one or more tire and/or axle is in overload.


RE the -2% yes I filed a complaint with NHTSA on that one.
Over the years I've attended at least 3 major RV shows per year. I take pictures and discus specifications with dealers and sales people.

Here are a couple of examples of just how far trailer manufacturers will push the minimums with tires.

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Old 06-05-2020, 01:39 PM   #86
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Geesh... Does anyone have ANYTHING to do out there in this ol' country? He made his rim/tire swap and all looks good for him and I think I am the only one to notice. Don't recall seeing a thread that has been so thoroughly hijacked!
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Old 06-05-2020, 04:00 PM   #87
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George, I usually buy into what you're saying (odd as that may sound), and this time I'd like to double up on the comment. CW and Tireman, please take this repeated discussion to the PM section. Normal folks can't begin to even scratch the surface of the information given. We all know that tires were y'all's lives. But enough is enough, please. CW has made every effort over the last many weeks to introduce other subjects. Tireman, surely you know about something else other than tires.....
I don't want this to sound as a personal attack by any means. I can personally attack Coors Light beer drinkers instead. Just let this thing go, please.
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Old 06-05-2020, 05:20 PM   #88
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George, I usually buy into what you're saying (odd as that may sound), and this time I'd like to double up on the comment. CW and Tireman, please take this repeated discussion to the PM section. Normal folks can't begin to even scratch the surface of the information given. We all know that tires were y'all's lives. But enough is enough, please. CW has made every effort over the last many weeks to introduce other subjects. Tireman, surely you know about something else other than tires.....
I don't want this to sound as a personal attack by any means. I can personally attack Coors Light beer drinkers instead. Just let this thing go, please.

Whaaat!!! Jim, JIM...PLEASE say it ain't so!! Attack Coors Light drinkers?? No, no. Do you not remember that Mark Harmon, head of NCIS, promotes Coors???? Careful...

But, yes, trying to push the discussion into the minutia when no one really cares I doubt is helping much. Cal has done his best to open up other areas of interest which I've found very interesting and beneficial.

Not pushing or taking sides but we've gone thru the Tireman vs CW dialogue before, and, back then, it reached the same point. If one has refuting evidence of something stated or posted (FMVSS) then by all means post those facts. If not, .......
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