Wheel Wells and Tire Failure

"Ditto on Kudos to Hal! He has been very helpful.... " Quoted directly from Dan

Dan, I take offense with your statement.  I haven't had cooties since I learned all girls in my grade school had them and you could get them by kissing the girls.

Hal

One more 2 cents on tire failure...
Yesterday I experienced a complete tire tread separation on the ST 215/75/R14 Carlise tire.  This tire was low mileage, garage kept, and the TM is towed at pretty close to advertised dry weight.  The tire pressure constantly is checked using a digital guage.

The tread came off cleanly in one piece depositing itself on the interstate and causing only little damage to the TM.  It is obvious from inspection of the remaining carcass that the tread bonding to the inner plies is very poor.  In a way this worked out because it came right off without tearing up the well.

As an automotive engineer I advise that the Carlise tire of this design can come apart at any time in spite of all due caution.  I'm getting Marathons and will use a Carlise for a spare.

Lol Hal, but I guess it was me who gave ya the cooties to begin with. But I really do appreciate your insight, thank you Hal!

Sincerely,

Happytrails..........

Just curious, was this a load range C or D? (50 or 65 psi) and was the trailer ever towed above 65 mph.  I have one Goodyear and one Carlise.  My 3124KS originally came with load range C's and after weighing it twice, I see why TrailManor went to D's on that model.  I'm just waiting for my 4th tire failure and I will find a truck tire.  I really do not understand the reason that the trailer tires are only speed rated to 65 mph.  I believe the minimum for a car tire is either 110 or 115 mph.  I think there needs to be some margin between actual speed and the tire rating as far as safety and durability go.

John, I believe the speed rating on the tire is because trailer tires are made of a different type of rubber. They are designed specifically what they're for......trailers, which spend a lot of time sitting. The special compound they're made of is made to resist the effect of sitting in one place for long periods of time. They also are designed to resist the effects of ultraviolet light better than regular tires, (I think). I believe the tires on mine are really old, but they're not cracked or dryrotted in any way. I'm probably going to replace them anyway before I put it on the road just for safety's sake.

Happytrails......

[Denny_A]

-------------------snip------------

I remember speaking with Michael Hulsey (the designer's son), when we shared an office (years ago), about the unique weight distribution for sway control (their website also mentions this).  Do you think TM inadvertantly sacraficed tire reliability for better sway control?

Or do the owners seem to find the tires over-loaded for this application?  I'm just guessing, but if there are only two tires, wouldn't a tire rated for at least 60% of the gross trailer weight (wet weight) be strong enough?  Does Load Range D make much difference?

I  was goaded into action by this thread. Since TM doesn't supply any "Marathon" paperwork from Goodyear regarding  their tire, I did a bit of searching on Goodyears website.  I was able to find everything but the "speed rating". A google search didn't produce anything either - but, that''s probably the searcher's fault.

The Marathon ST215/75 R14 tires are Load Rating C, 6 polyester plies and MAX load at 50 psi (which is the cold inflation px limit) is 1870 lbs (omigawd!).

If one cares to do the math, for a 2720SL, it would be noted that  2680 dry + 1394 load cap = 4074 lbs. Two tires x 1870 lbs = 3740 lbs.

It seems to me that  every single trailer with a single axle can be overloaded. Range is from 3992 lbs to 4074 lbs, up to the model 3023. The 31 series range from 4412 lbs to 4685 lbs on a single axle. They must have a Load Rating of D, at least, for the tires to hold up, and 65psi operating pressure.

Still in my particular case, I can overload my tires by 334 lbs total, if in accord with TrailManor.

I discussed this with JD at TrailManor, among other issues when returning his call. He also noted that the axle limit (I assume he means the Torflex) is, are you ready - 3500 lbs. This can't be correct. No trailer has a max gross weight under 3992 lbs. Fortunately my minivan is limited to 3500 lbs, so it represents no problem for me.

If the info I gleaned from my tires and from Jimmy Davis is correct, it's possible the tire failures are not the fault of the tire. As in overweight , means overheat, means early fatigue, etc. Or, axle overlaoded means dynamic response is affected, adding stress to tires, etc.

If the tongue weight were, say 480 lbs, and the Wt Dist Hitch place 1/3 (160 lbs on the wheels), and 320 lbs on the tow vehicle, you'd be safe up to 3960. Still that wouldn't take care of the axle problem.

All kinds of things come to mind, none of 'em good! So, if MAX load = 1870, really IS the "max load", and not some % of the actual safe load (say 66.6% of failure load), then many folks could be hangin' it out while keeping loads within TM's limits.

I must be missing a key piece of info! Feedback anyone?


Denny_A

Denny_A,

Have you asked TM about this? Surely something must be missing from the equation or you have uncovered a major design flaw with our TMs that I would consider to be totally unacceptable from a customer standpoint. These things aren't cheap to be under engineered. They should be over engineered for the price they charge. This loyal group needs an answer (a correct answer) to this issue and it should be in writing.

Wade  

I agree completely Denny!!

I didn't see any math errors or flawed assumptions....

All the more reason to weigh the trailer and get a good idea of the actual weight.

I think someone wisely posted something a while back (could have been Hal?) about carrying as much as possible in the tow vehicle.  I do my best to heed this advice and am very careful about the accessories I purchase, tools I carry, pots & pans, etc.  I try to find the lightweight solution whenever possible.

On a slightly different note, both used trailers I've inspected have suffered blow outs on the curb side.  Seems that the load would be more on the street side where the water tank is located?  Perhaps the tanks is empty and the cabinets are full more often than not?  Just curious observation

[Denny_A]

Denny_A,

Have you asked TM about this? Surely something must be missing from the equation or you have uncovered a major design flaw with our TMs that I would consider to be totally unacceptable from a customer standpoint. These things aren't cheap to be under engineered. They should be over engineered for the price they charge. This loyal group needs an answer (a correct answer) to this issue and it should be in writing.

Wade  

Haven't asked. It was this Wed. that I heard about a 3500 lb axle limit from JD. I can only guess that he was mistaken - or sumpin'! Even when I told him that didn't seem right, he didn't waffle. As honest and helpful as he is, I have to believe it for now.

I think a call from me, to Mike Hulsey, is in order - for axle rating specs.

Will post results when available.


Denny_A

[Denny_A]

I didn't see any math errors or flawed assumptions....

All the more reason to weigh the trailer and get a good idea of the actual weight.

--------snip---------

There was a 100 lb math error (tire's favor) which saves the tires a bit.

If the trailer has a 4074 Lb max gross wt, and 320 lbs of the tongue weight is transferred to the tow vehicle, and 160 Lbs to the trailer, the load on the trailer tires is  Wt = 4074-320 = 3754 Lbs.

I've assumed 480 lb tongue load + 3594 lbs on the tires = 4074 lbs, when the trailer is disconnected.

Therefore, if loaded symetrically, each tire sees 1877 lbs.  Seven lbs over, per tire. That's for the trailer with the highest max gross wt allowance (31 series excluded).

Maybe the exercise I went thru is much ado about nothing - if the axle's max is a few hundred lbs more.


Denny_A