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Old 04-29-2021, 07:43 PM   #21
sourdough
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Originally Posted by Tireman9 View Post
As an actual Tire Design Engineer I can assure you that there is more misinformation or partially correct information out there than technically accurate information.

It is true that the original tire selection is the responsibility of the RV Mfg. The issue is that once the RV is sold it seems that most RV Manufacturers have little or no interest in standing behind their choices with any actual warranty service when it comes to tires.


It seems that OE tire selection for RVs is based on one goal. Find the smallest, lowest cost tire that will meet the requirements.


The only Federal (DOT) requirement is that the tire load capacity be AT LEAST equal to the maximum load rating of the axle. While RVIA now requires 10% extra capacity, DOT does not. As a point of reference most cars come with a 20% to 30% or higher Reserve Load capacity



A smaller tire can mean the RV Manufacturer can get away with less costly (smaller) wheel well so this is extra pressure on purchasing to get the minimum possible tire that can meet the requirements.


Given the above, it is up to you, the owner, to decide if you want any, some or more "Reserve Load capacity" for your RV. You may have the option of larger tires or you may be restricted to trying to find tires of the same dimensions but with higher load capacity.


You need to educate yourself about the requirements and limitations of the four "types" of tires that are in the market. 'P" is Passenger type. If used on an RV (trailer or motorhome) the load capacity Must be reduced by dividing by 1.1 but not everyone will know or do that. LT type can be used in RV service but you will soon discover that LT tires with the same dimensions and Load Range (ply rating) have a lower load capacity than the same dimension ST type.
ST type have the highest load capacity rating for a given set of dimensions, but you need to remember that the ST tire Load formula that is used to calculate the tire load capacity is based on an assumption of a 65 MPH Max speed. We all know that there is "No Free Lunch" and the trade-off for increased load capacity is lower speed capability. The "Speed Rating" symbol on many ST type tires is based on a 30 minute test so you need to decide if you want to depend on such a short term test when making a tire selection.
Finally there are actual "Truck / Bus" tires. These have no leading letter and are usually on 17.5" or larger wheels. These tires have higher Load Range, usually F or higher These tires are almost all rated for 75 MPH in RV use on the highway.


Do your homework. Ask questions, but remember there are very few really knowledgeable people out there who have the training or experience in tire engineering. Just having driven on tires for 40 years is not the same as having been held responsible for designing tires for Truck, Passenger, Trailer, or Indianapolis racing application. Also, being able to read Federal Regulations is not the same as having to work within those regulations while meeting the goals and demands from GM, Mazda, Toyota, Honda, Freightliner, MB, Nissan, Ford, or Chrysler.

Roger is there some reason you upsized the fonts for your post (shouting?)? We all use regular fonts and the community rules have guidelines on them - you might read those. Everyone's thoughts/opinions carry the same weight upsized fonts or not.
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Old 04-29-2021, 08:55 PM   #22
JRTJH
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Originally Posted by fjr1300 View Post
Recstuff.com has four styles of 15" 6 lug wheels rated for 3200 lbs.
Thanks for the info... I went to recstuff.com and sure enough... Those are Sendel wheels, also listed on their website... Easy, right ??? NOPE !!! I used the Sendel part number, and looked them up on the Discount Tire site. Same model/part number is listed for the same price, $119 each, but on the DT site, those wheels are rated at 2830/80PSI... I sent an email to DT asking if their specs are correct, so we'll see.... Tomorrow, I'll check with Sendel to get their specs as well.

Anyway, thanks again for the link. Hopefully it'll lead to an answer....
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Old 04-30-2021, 12:06 AM   #23
CWtheMan
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Originally Posted by JRTJH View Post
I haven't been able to find wheels rated at 3080 pounds that are 15" 6 lug. Do you know of any?
They can be found somewhere on this page.

https://www.carlislebrandtires.com/o...trailer-wheel/
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Old 04-30-2021, 01:09 AM   #24
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Being an expert on how tires are built does not indicate expertise on how tires are governed or how those regulations are linked together with tire industry standards.

The National Highway Traffic Safety Administration (NHTSA) is the arm of the DOT that establishes vehicle safety standards, including tires. They are numerous standards controlled by NHTSA. They established the Federal Motor Vehicle Safety Standards (FMVSS) to insure minimum tire standards are observed. They also administer the documents in SAFECAR.

NHTSA uses mandatory mandates to insure consumers are aware of important tire industry standards that are spelled-out in various FMVSS standards. The following paragraph is a mandated mandatory safety notation about tire designated sizes. It is found in all vehicle owner manuals. If you look at the USTMA industry standards for replacement tires you will also find that statement.

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”.

The ST tire manufacturers have acted quite favorable to the needs of load capacity reserves for RV trailer tire fitments with the addition of load ranges with higher PSI ratings for more load capacity within a designate tire size; Such as the ST25/75R15 having load range letters C, D, E, and F.
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Old 04-30-2021, 03:49 AM   #25
flybouy
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Originally Posted by JRTJH View Post
Thanks for the info... I went to recstuff.com and sure enough... Those are Sendel wheels, also listed on their website... Easy, right ??? NOPE !!! I used the Sendel part number, and looked them up on the Discount Tire site. Same model/part number is listed for the same price, $119 each, but on the DT site, those wheels are rated at 2830/80PSI... I sent an email to DT asking if their specs are correct, so we'll see.... Tomorrow, I'll check with Sendel to get their specs as well.

Anyway, thanks again for the link. Hopefully it'll lead to an answer....
I looked at the Sendel site and now they list 2 rims in the style I have with 2 weight and psi ratings and different part numbers. http://sendelwheel.com/wheels/t03sm.html. For me it's academic because I don't need the extra capacity.
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