Tire weight capacity question

[boje]

Am I figuring this out correctly?

GY Marathon tire capacity 3420 per tire = 13680
3400RL = 12460
Carrying capacity = 3290
Hitch = 2060

3400RL + CC = 15750 - hitch = 13690
GY Marathon capacity 13680
10 lbs.

Cutting it close if I figured it right.

[Tom S.]

Here's a few things to consider. You figures assume you load the trailer to capacity. Depending on how you load the trailer, the pin weight can change. More weight in the front adds to the pin weight and becomes distributed between the truck and the trailer. More weight in the back lessens the pin weight and is added to the trailer. The best thing you can do is load the trailer with what you normally carry, including groceries, water, etc. and take it someplace to get it weighed. Then you will know exactly what kind of weight is on the trailer tires.

Also remember that a tire isn't going to fail because you have a few more pounds weight on it than what it is rated for (I'm talking a few - not 100's) because of a built in safety factor. If you are still uncomfortable, the ratings you cited are for "E" rated tires and you get higher rated like "G" or even "H" - but prepared to pay!!!

[Glenn and Lorraine]

You don't figure the weight carried on the tires using total trailer weight. You must consider the fact that a lot of the trailers weight is also carried, via the hitch, by the TV.
To get a true weight of the tire load it is best to have each axle weighed. These numbers are your starting point to establish the weight load on the tires. Using those numbers, you would than use a tire load range chart for your tire size and load range to establish proper air pressure.
OR for more exact numbers weigh each tire load.

I should also note that increasing the load range from E to G or increasing tire size does nothing for the capacity of the axles. By increasing the load range or size will make the tires safer but not so with the axles.

[bigmurf]

Calling the "tire police".

[Art-n-Marge]

boje. To correlate your math with the pin weights mentioned above by Glenn and Tom you need to modify your mathematics as described below:

NO CHANGE: GY Marathon tire capacity 3420 per tire = 13680
NO CHANGE: 3400RL = 12460
NO CHANGE: Carrying capacity = 3290
NO CHANGE: Hitch = 2060

REMOVE THIS EQUATION 3400RL + CC = 15750 - hitch = 13690... and replace with:

NEW: 12460 - 2060 = 10400 (weight on tires)
NEW: 2060 / 12460 = 16.5% (percentage of weight at the pin)
NEW: 3290 - ( 16.5% x 3290) = 543 (approximate Cargo weight carried at pin)
NEW: 3290 - 543 = 2747 (approximate Cargo weight carried on trailer tires)
NEW: 10400 + 2747 = 13147 (approximate total weight carried on tires)

GY Marathon capacity 13680
REMOVE THIS BECAUSE IT IS INACCURATE 10 lbs.
NEW VALUE +533 lbs which is the Marathon capacity minus the new calculated weight carried on THE WHEELS. You are well within the calculated weight.

These are only paper estimates. If you actually load your rig you might find that the documented weight difference will put more of your cargo on the PIN, not the wheels. While this is good news for the trailer's tires since they will be carrying less weight, depending on your vehicle, you might be putting too much weight on its rear wheels. You need to know your TV's RAWR will not be exceeded, AND that the GVWR is also not exceeded.

For fifth wheels, manufacturers document a pin weight as 15% of the trailer's GVWR. You might find us MOCers are finding that the percentages are about 18% to as high as 25% depending what you carry.

For example, if you add a second AC, and a Washer/dryer and a generator, all this adds substantially to the pin weight.

Only a scale will tell you what you really have.

[LonnieB]

quote:By bigmurf

Calling the "tire police".

[Art-n-Marge]

I forgot to mention the axles. The rated weight of the axles of new Montys is either 6500 or 7000 lbs per axle. That means the totals are 13,000# and 14,000# of capacity. The 6500# axles are not enough for your trailers as we calculated them (about 147 lbs over or 37 lbs per axle). But you might find in actuality if the percentage on the pin goes higher, then the actual weight on the RV tires would put the rig under the 6500# rating. If you can confirm the RV has 7000# axles, there is nothing to worry about.

3,290# is a LOT of weight. Clothing, personal items, tools, a few games, dinner settings, pots/pan, kitchen gadgets and all the food pantry and refrigerated do not get close to that amount unless you intend to pack every shelf, cabinet and opening which is not practical. Much of the weight can be saved by traveling with empty tanks (except a few gallons in the black to keep the cleaning solutions working correctly and maybe a little in the fresh water for using during potty breaks along the route. But I am starting get off topic and will wait if you ask the MOC for help on how to lighten loads.

[boje]

Thanks for all the info. I have a call into Keystone, and just wanted some feedback from them on the Marathons. Search GY Marathons on any search engine, and I cringe at the feedback from previous owners. I guess I am nervous as we have our first legit road trip coming up next month. I did just purchase a tpms for piece of mind though.

Thanks again.

[KathyandDave]

Did somebody call the weight police?
The carrying capacity numbers just confuse me, since they depend entirely on factors that vary daily. Since everybody's situation varies (TV model, Monty model, number of cats and dogs, amount of beer in cooler, etc.), all one can do is to get your stuff and your loved ones on board, then weigh the TV front and rear axles without the Monty, then hook up the Monty and weigh front and rear axles again and weigh the Monty axles as a pair. Every other answer flows from these numbers: single or dual axles on the TV; safety and performance limits for tires, axles, hitches, etc., whether you can add a heavy thing like a genny, whether you're in bounds for your drivers permit; how much you have to pay for vehicle permit; etc., etc., etc. The MOC has an enormous amount of knowledge about this stuff that you can search on or post questions, always with the caveat that your decisions are your own and your mileage may vary.

[Art-n-Marge]

boje,

Regarding tires you could start a whole other can of worms.

The Goodyear Marathon STs will do fine. Let's all just keep saying that together since I have some too. They are better than others as I am sure there are others better than them. Just keep them inflated at 80#, keep the speed under 65, avoid curbs, avoid "torquing the wheels" and they will run as specified. Check the date of manufacture to get a pretty good idea of how long they should last (5 years is typical).

[8.1al]

bojoe,
That pin weight is for an empty trailer, as you load it that will go up. I would be willing to bet that when at max GVW the pin weight will be 3000lbs of more.

[boje]

Art-N-Marge

Can you clarify the "torquing the wheels" comment?

Thanks

[Glenn and Lorraine]

quote:Originally posted by bigmurf

Calling the "tire police".

"TIRE POLICE"??? Didn't know there was such an organization.
Can I join?? Where do I get an application??
I would be proud to be a member of such a elite organization.
Unlike some Internet "police" organizations, I am sure that the "Tire Police" are members with many many years of hands-on experience in the tire industry.
Some of the other Internet police organizations, which I will not name but we all know them, quote misplaced, misunderstood facts that do not necessarily apply to all factors of their jurisdiction. In actuality their information is more hear say than factual. Hear say carries no weight in a court of law. As that famous cop of Dragnet fame, Jack Webb, used to say "The facts ma'am just the facts"
Whereas the more experienced Tire Police give accurate factual hands-on information garnered from years of experience selling and servicing tires that apply to anyone that operates at motor vehicle and may or may not also tow some form of trailer be it a cargo trailer or even an RV.
If the head of this fine organization would send me an application using my PM or Email as listed above I will most certainly fill it out and return it ASAP.

How about you Lonnie, do you want an application too?

[LonnieB]

quote:Originally posted by Glenn and Lorraine

How about you Lonnie, do you want an application too?

You bet Glenn, I would consider it an honor to become a member of such an elite organization.

[Glenn and Lorraine]

Lonnie, That didn't take long. Turns out the the Tire Police Commandant monitors the MOC forum on a regular basis. He saw my request and contacted me immediately. He indicated that from what he has seen here there is no need for either of us to apply. They gathered enough info on both of us to just go ahead and makes us members. Even waved the initiation dues.

this is my badge...


here's yours...


Take note that our badge numbers are the same as our MOC #

[LonnieB]

That's great Glenn. I will print mine out, have it laminated, and carry it in my official Tire Police wallet.

[sreigle]

As point of reference, our 3400RL weighs (CAT scale) 14,620 fully loaded. Our pinweight is 2860, leaving 11,760 on the two axles. If the weight is evenly distributed (not really likely), then each tire is carrying 2,940 pounds. Given that one axle probably carries more than the other, to at least some degree, it's still cutting it a bit close.

[Art-n-Marge]

I think the tire on the badge should have a blow out.... naw just kidding - these aren't Chinese made badges. But seriously, maybe the acronym MOC should be on there somewhere?

Boje,

Torquing the tires is a slang expression I use for when you back the trailer up at an angle causing the trailer tires to be slanted off the vertical (torqued) because of the stress of turning on axles that do not turn with it. You'll notice that, especially the inside tires of a turn and they will have a slight slant, usually in opposite directions and are no longer straight up and down because of it.

It has been recommended to me by many RV savvy folks that after making this kind of turn, to straighten out the rig as much as possible by going further, then back in the desired spot in a straight direction. This helps the axles, wheels and tires to return to a completely vertical position and relieve the stress caused by the torquing move. I was told by these same folks that leaving tires in a stressed aspect can weaken them over time because the tires are not sitting on their bottom but on their sides more than they should.

I hope I explained this right. The Tire Police might have a better terminology for this.

[8e3k0]

Art, in this application I would be more concerned of the stress and torque on both the shackles and leaf springs then the tires at, say 80 or 110 psi. Just watch a tri axle when the TV is at 90 degrees to the loaded trailer; some wicked scooting and stresses on tires, rims, hubs, shackles, springs etc. Those axles will move 2 to 3 inches out of alignment with hope that when you straighten out your rig that the alignment comes back to normal.

[Art-n-Marge]

You are right 8e3k0! Since we were talking about tires I tried to keep on topic. Tires are an obvious visual check when you are driving. Just seeing the tires undergo what's happening should remind us that straightening out is needed otherwise it does impact all the other suspension components even moreso (after all tires are made of flexible rubber) and most suspension components are mostly metal - axles, shackles, springs, etc.

For Boje, these are other things to think about why "torqued wheels", should be watched for. So does anyone know a better term?