Am I calculating this correctly?

[Don_Z]

Over the weekend, I went to a local RV show and walked through 3 floor plans from Grand Design RV, makers of Solitude 5th wheels. I noticed they were equipped with LT235/85R16 tires.

They didn't have any brochures about their units so I went online after returning home. The 2 larger trailers (both listed as 38'11") are equipped with 7K axles. GVWR for these trailers is 16K, hitch weight is listed at 2600 pounds.

Gross weight 16K - hitch weight 2600 leaves 13,400 for the tires to support, but E load range tires would max out at 12,168. So...is this unit set up for tire failure right off of the assembly line?

Don Z.

[sk734]

I am glad to see some more LT tires coming on board-Westlake. Someone needs to analyze these-where is NCHauler!!

[Mont_G_J]

As far as I'm concerned, the manufactures' quality of materials and build is stamped right on the side of the tires.

[wilber1]

Allworth wrote:
And we all know that any tire that is overloaded by just 1 pound is going to fail instantly!

Not likely but we have people talking about using an 80% rule concerning our TV GVWR's, which are already only around 80% of their axle and tire ratings, but hauling trailers that are almost maxed out on their axle and tire ratings is perfectly OK. :h

[Allworth]

And we all know that any tire that is overloaded by just 1 pound is going to fail instantly!

[gmcsmoke]

2008Wildcat wrote:
Everyone always knows better than the manufacturers.......

Too bad there isn't an agency that would keep watch over these issues.

Oh, what, what is that called..?? RVIA??

Hmmm.....no one ever claims that they use the very best available to them, but then we all would ***** and complain that the coaches are too expensive!!

If you don't like what they use, go buy what you want on there!!

I don't get the issue here.

If they would be using a C range tire, I could understand the issue, but if they are covering their GVWR, they are doing it right. Overkill? No, but covered...

qft

[wprice5441]

Don per your link to the trailer specs what you are doing is listing the dry weight for pin weight, the dry weight for the trailer is 12750. The total load carring capacity is 3250 lbs. All this weight will not go on the axels. they show the pin weight at 20.4%. Using this same formula for gross weight the pin weight would go up to 3840 (16000 x 20.4%). This would leave 12160 left on the axels. This is a safe margin if your trailer is loaded to max and the weight distributed correctly. When you load the trailer to your normal use then weigh the pin and axel weights at a truck scale. You are safe if loaded correctly although I have this same weight and I made them upgrade to G rated tires even though the factory rep explained these facts to me. I had to pay a good bit more but that was for my satisfaction not because I had to. As listed the trailer is safe for E rated tires.

[gitane59]

All you need to know and remember is 3 things.
1. The manufacturers stock tires are for delivery purposes only since the vast majority of RV owners choose to park their new units and use them a seasonal cottages
2. Because of fact #1 the manufacturers stock tires will be the absolute minimum spec required and the cheapest supplier sourced tire bidder.
3. The RV transport company driver has no reason whatsoever to follow the 65 mph maximum speed rating of the vast majority of ST tires as time is money for those guys and the risk of a speeding tickets outweighs the time factor.

With these facts in hand why RV'ers who plan to tow their units rather than use them as park models don't demand optional upgraded tires at time of purchase or as a condition of purchase is beyond me.

To each their own, but in my mind towing confidence with quality tires with weight capacity to spare is priceless.

The OP is correct to be asking these important questions and hopefully will make the right decisions when it comes time for them to purchase.

[clc530]

All the blowouts on the Westlake tires where LT (2007)tires not ST, I have noticed more 18 wheels using Westlake tires. Could it be Poor Maintenance on the 5th wheels just saying.

[Atom_Ant]

clc530 wrote:
Tim Fry, senior development engineer with Goodyear Tire & Rubber Company stated, “The major difference is reflected in the polyester cords used in ST tires. These cords are bigger than they would be for a comparable P or LT tire. Typically, the steel wire also has a larger diameter or greater tensile strength to meet the additional load requirements. Because of the heavier construction for an equal volume of air space, an ST tire is designated to carry more load than a P or LT tire.” Taken from RV 101 good read http://rvingwithmarkpolk.com/2012/11/08/trailer-towing-st-tires-vs-lt-tires/

The engineering and design means nothing, absolutely nothing, when you outsource to the Chinese with inferior raw materials. We are now having trouble with Chinese wheel bearings failing within 6 months. How much more do we have to take!

[clc530]

Tim Fry, senior development engineer with Goodyear Tire & Rubber Company stated, “The major difference is reflected in the polyester cords used in ST tires. These cords are bigger than they would be for a comparable P or LT tire. Typically, the steel wire also has a larger diameter or greater tensile strength to meet the additional load requirements. Because of the heavier construction for an equal volume of air space, an ST tire is designated to carry more load than a P or LT tire.” Taken from RV 101 good read http://rvingwithmarkpolk.com/2012/11/08/trailer-towing-st-tires-vs-lt-tires/

Me Again wrote:

2008Wildcat wrote:
They are Westlake St tires, rated at 3520 lbs @ 80psi.....

Take into consideration the dry pin weight and you have plenty of coverage.

And you should plan on either replacing those tires fairly soon or you will be experiencing a failure. This is yet another manufacturer providing the bare minimum tires to get it to the dealers lot and into your hands. There is the deal on Westlake.

Private Brand---Tire Seller------------------Tire Maker
Westlake---------Foreign Tire Sales------Various off-shore

Westlake tires are import by a company called Foreign Tire Sales and come from various different off-shore plants! Quality can vary depending on the plant of the week/month/year that produces the tires.

Look at this Westlake ST 14 ply rated: Westlake LRG 14 ply This tire is rated to 4080 pounds single for $165. What do they know that Goodyear fails to know about their G614 rated to 3750. What did P.T. Barnum say? Google Westlake ST tire problems for many mixed reviews.

If they have an option for LRG tires and you are ordering one, then spend whatever they want for that upgrade. There will not be a cheaper time to do it.

If you decide that you will upgrade right after purchasing it yourself, make sure the OEM wheels are rated to 3750 and 110 inflation or you will also be footing the bill for upgraded rims.

Regarding 2008Wildcats "you have plenty of coverage", I would not say that 40 lbs per axle(7000lbs) extra is plenty of coverage. A small in-balance left to right would overload a tire beyond its rating. Tire people like Carpriracer, Tireman9 and Fasteagle say that you should have 15 percent or so extra capacity. 40 lbs of excess capacity on a 7K axle is 0.6 percent!!!

This is just all common sense. You get what you pay for. Trailer manufacturers are buying these tires and wheels for next to nothing. They probably pay around a 100 dollars for an 16" aluminum wheel and LRE ST tire pre mounted from Tredit or Tireco buying truck or train car loads at a time. The get the frames in without tires and wheels, in stacks of 3-5.

Pressure from brand user groups giving feedback to their trailer manufacture is been becoming more effective with more and more manufacturers offering factory upgrades to LRG tires and switching all wheel purchases to wheels rated to 3750 and 110 inflation. Our Cardinal group leader does regular visits to the Cardinal factory and Cardinal sends people to our rallies, bringing new models for viewing. All trailers now have the upgrade wheels and the option for LRG tires is available.

We can fix this issue! Just say no to cheap tires!

Chris

[2008Wildcat]

LI Happy Camper wrote:

2008Wildcat wrote:
Everyone always knows better than the manufacturers.......

Too bad there isn't an agency that would keep watch over these issues.

Oh, what, what is that called..?? RVIA??

Hmmm.....no one ever claims that they use the very best available to them, but then we all would ***** and complain that the coaches are too expensive!!

If you don't like what they use, go buy what you want on there!!

I don't get the issue here.

If they would be using a C range tire, I could understand the issue, but if they are covering their GVWR, they are doing it right. Overkill? No, but covered...

:S :S :S :S :S :S :S

LMAO

Do they have the "beating the dead horse" smiley on here.....??

[LI_Happy_Camper]

2008Wildcat wrote:
Everyone always knows better than the manufacturers.......

Too bad there isn't an agency that would keep watch over these issues.

Oh, what, what is that called..?? RVIA??

Hmmm.....no one ever claims that they use the very best available to them, but then we all would ***** and complain that the coaches are too expensive!!

If you don't like what they use, go buy what you want on there!!

I don't get the issue here.

If they would be using a C range tire, I could understand the issue, but if they are covering their GVWR, they are doing it right. Overkill? No, but covered...

:S :S :S :S :S :S :S

LMAO

[Atom_Ant]

People are always telling me that they use cheap stuff because I would complain about price otherwise. I've never complained about price for a quality product. I think the need to stay competitive is ficticous from the leather chair of a CEO that doesn't get out much.

It's like the airlines that keep cramming me into thinner, tighter, lighter seats to stay competitive, yet I have never shopped or complained about price. I'm far more interested in schedule.

[2008Wildcat]

Everyone always knows better than the manufacturers.......

Too bad there isn't an agency that would keep watch over these issues.

Oh, what, what is that called..?? RVIA??

Hmmm.....no one ever claims that they use the very best available to them, but then we all would ***** and complain that the coaches are too expensive!!

If you don't like what they use, go buy what you want on there!!

I don't get the issue here.

If they would be using a C range tire, I could understand the issue, but if they are covering their GVWR, they are doing it right. Overkill? No, but covered...