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Old 11-02-2015, 06:10 PM   #181
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I understand the concept that when a wheel is only marked with a max load then there is an assumption being made by someone about the tire size.
I would think the wheel supplier would not agree that any inflation is acceptable as long as the load is not exceeded so if pushed I think they would provide some answer.
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Old 11-02-2015, 06:12 PM   #182
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I merely referred to what my underwriter reflected upon. There is no question here about what excuses the insurance business does or does not do to avoid liabilities.
Similarly one cannot have a vehicle re-certified for carrying extra weight in a trailer by adding a heavier suspension, air bags or extra leaf springs and changing P rated tires to LT tires.

"increasing pressure in the tire apparently by all literature does not increase load carrying ability of the wheel itself.

Your wheel may have a max load capacity number stamped on it. I would contact the wheel company concerning wheel load & inflation capacity which is separate from tire load, inflation and speed capacity"


I'm pretty sure i said tire but it should have perhaps read tire and wheel assembly.

"Special Trailer (ST) Tire Speed Ratings

Industry standards dictate tires with the ST designation are speed rated to 65 MPH (104 km/h) under normal inflation and load conditions.
However Goodyear Marathon and Power King Towmax STR tires featuring the ST size designation may be used at speeds between 66 and 75 mph (106 and 121 km/h) by increasing their cold inflation pressure by 10 psi (69 kPa) above the recommended pressure for the rated maximum load.

Do not exceed the wheel's maximum rated pressure. If the maximum pressure for the wheel prohibits the increase of air pressure, then maximum speed must be restricted to 65 mph (104 km/h).

The cold inflation pressure must not exceed 10 psi (69 kPa) beyond the inflation specified for the maximum load of the tire.

Increasing the inflation pressure by 10 psi (69 kPa) does not provide any additional load carrying capacity."

http://www.tirerack.com/tires/tirete...jsp?techid=219
one of several sites offering the same information as my agent passed along.

For me this means making the tire stiffer with air will not permit overloading of the max limit of the tire which apparenlty is limited to what the tire is mounted to for air pressure....

for instance i would think that if we had 110 psi max tires and my rims were limited to 80 - we would have to fill those tires carrying the 110 psi max to a max of 80 psi or risk the rim failing.

Would i be correct?

IMO the tech bulletin from Goodyear only applies to Goodyear Marathon ST type tires and not to any other brand or design of tire and certainly not to a wheel.
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Old 11-02-2015, 06:41 PM   #183
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There is another side to the coin.

Tire manufacturers are required to list rims that fit every tire size they make (individually). Rim manufacturers are not required to provide load or psi limits on their rims. So, anyone with rims provided with OE tires must assume that the rims are qualified for the OE tires and any other tire of the same size can be used. OOPS! The other tire even though the same physical size may have a higher load capacity requiring increased inflation pressures. What to do? The rim manufacturer is required to put part numbers and serial numbers on his rims. When in doubt, get those numbers and call the rim manufacturer.

Some times OEM providers of rims will yield to the wishes of the vehicle manufacturer and put load capacities and psi ratings on OEM rims to that manufacturer. Usually an entire line-up of a model of RV trailers can be fitted with the same size tires. Other times the line-up is so long that the larger end will require larger tires and rims. To help keep their order sorted correctly the rims will be marked to match the tires. That way all tire/rim combinations can be shipped in lots for an entire production line.
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Old 11-02-2015, 07:37 PM   #184
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Clarification
Each size tire shown in industry standards such as Tire & Rim Association list the range of rim width the tire size is approved for. i.e. 5.5 - 7.0 might be the rim width for one size.
I am not sure that every wheel is capable of handling the load of every size tire made that might be put on a specific rim. They might be but I wouldn't just assume the wheel is OK.
The 16" GY LR G tire is a good example. I doubt that every 16x 6 rim is OK for 110 psi.
I do agree it is best to confirm wheel part number capability with the wheel company.
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Old 12-19-2015, 07:32 AM   #185
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On a tire that is stamped 3750lb does that mean the camper can only carry 15,000lbs.


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Old 12-19-2015, 07:38 AM   #186
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On a tire that is stamped 3750lb does that mean the camper can only carry 15,000lbs.


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Keep in mind that a certain percentage of your total trailer/5th wheel weight will be carried by your tow vehicle. If using the tire weight capacity as the only factor of how much your trailer can weigh, you can weigh more than 15,000 pounds -- how much more depends on what percentage of your trailer weight is at the front.

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Old 12-19-2015, 12:48 PM   #187
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Originally Posted by nomad297 View Post
Keep in mind that a certain percentage of your total trailer/5th wheel weight will be carried by your tow vehicle. If using the tire weight capacity as the only factor of how much your trailer can weigh, you can weigh more than 15,000 pounds -- how much more depends on what percentage of your trailer weight is at the front.

Bruce
You should have a sticker / plate with the stated GVWR which is the max total weight. Tires do not carry an average of total/number of tires as axle loads are not 50/50 side to side or even 50/50 between axle.

A good rule of thumb is to run no more than 85% of the max load number based on actual scale readings of individual tire loading.
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Old 12-19-2015, 11:37 PM   #188
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Once you own a trailer the total weight of that trailer is your responsibility.

It’s manufacturer will determine - according to safety regulations and standards - what it’s maximum/minimum load capacities are. Once they do that they will put the most pertinent information on the trailer’s federal certification label. On trailers, that label is found on the LH forward external portion of the trailer. It will have the GVWR, all GAWR values, tire and rim sizes appropriate for each GAWR and the recommended inflation pressures for those tires so that they will equal or exceed the requirements of each GAWR.

Somewhere in the other information provided to the buyer there is a vehicle manufacturer’s established hitch weight. It can be in the form of a range or a specific number. If a range has been used the lower figure is added to total GAWR. The sum must equal or exceed the trailer’s GVWR. After the trailer has been sold all hitch weight figures are the responsibility of the owner.

What is often misunderstood is certification. In this context it’s something official. By affixing the certification label to your trailer it’s manufacturer has affirmed those standards have been met and are the maximum/minimum standards for that trailer.

Often times you will see posts where owners are wondering why a tire retailer wont replace ST tires with LT tires. It’s because they know the tire design has been set by the manufacturer and is on the certification label. It’s also why tire industry standards require replacement tires to have, at a minimum, the amount of load capacity - by inflation - of the OE tires.
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Old 12-20-2015, 07:41 AM   #189
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I was going to buy a Cedar Creek 36CKTS, I have a 32RL now and I have Goodyear G614 on the camper now. What I was going to do was trade out the tires when I brought the bigger camper but I know I can't do that now. My tires are rated at 110lbs of pressure, is 3750lbs. That is 15,000lbs and that is great for my camper, GVWR, I think. My camper total weight of everything is 15,000lbs which will never happen. That's with all tanks full. The new camper is total weight 16,000lbs, so I will have to put Goodyear H rated tires on new camper and 17.5 tires. I think the new Cedar Creeks come with 17.5 ST tires made in China. I plan to stick with Goodyear tires that's made in America


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Old 12-20-2015, 12:16 PM   #190
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Slight clarification on the ST - LT tire change topic.
As a tire engineer, I see no reason for an owner to not be allowed to change type tire i.e. P to ST or LT or change ST to LT as long as the new tire at its inflation has equal or greater load capacity to the OE tire at its inflation and the max inflation capability as identified by the wheel manufacturer is not exceeded.
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