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Old 10-20-2014, 12:58 PM   #57
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With our Michelin 16s on the Eddie Bauer, we run 68 psi when loaded with full water, propane, and personal gear. If we add ~350# for a bike, we raise the tire pressure to 72 psi. In either case, I note that at 60 mph sustained driving on the freeway roads that the pressure increase has not exceeded 5 psi hot. No signs of sway at either pressure setting.

I am more concerned about the temperature differential between the edge of the tread and the center of the tread; sometimes, there is 10 degree F more in the center ... it seems like that would indicate that I need more pressure in order to reduce the flex in the center of the tread ???
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Old 10-20-2014, 02:24 PM   #58
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My 2012 21'Bambi recommends 65# for my 16" wheels. Weight of loaded trailer is 4500#. Just replaced them at 19,500 miles with edges worn out. I would say the 65# recommendation is too low.


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Old 10-20-2014, 03:28 PM   #59
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My 2012 21'Bambi recommends 65# for my 16" wheels. Weight of loaded trailer is 4500#. Just replaced them at 19,500 miles with edges worn out. I would say the 65# recommendation is too low.


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How did you get 16" wheels on your Bambi and where specifically did the 65 psi recommendation come from?

Your single axle Bambi at 4500# puts on more load per tire than my 6520# tandem axle Flying Cloud so 65 psi with 16" tires may be low for your particular Airstream.
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Old 10-20-2014, 03:36 PM   #60
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Travel trailer tires at max sidewall pressure. Is there a reference to support that?
Yes. I have a post on the solid technical reason behind advising that multi axle trailers should use the inflation on the tire sidewall associated with the max load. Nov 20 2013 Its called "Inter-Ply Shear"

Also one on what you need to do to switch from ST to LT tires June 23 2014
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Old 10-20-2014, 03:42 PM   #61
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First Google gave a manufacturer's load and pressure table for trailer tires:

Trailer Tire Load/Inflation Chart | Maxxis USA
The Load/Inflation charts establish the minimum inflation to carry the load and are OK for single axle trailers as far as I know.

For multi-axle trailers the tables do not take into consideration the unique cornering forces placed on the belt package.

You certainly should ALWAYS have more air than the minimum to support the load for straight running. Some would suggest you need at least 15% safety margin on the load and in addition set your cold inflation to 10% above that to allow for day to day temperature variations.

Ever wonder why Motorhome users are told 7 to 10 year tire life while trailer owners are told 3 to 5? Its called Inter-ply shear
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Old 10-20-2014, 03:46 PM   #62
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Just my opinion here, but I always compute needed tire capacity based on the GVW of the trailer to be on the safe side. And then there's the transient weights that occur when on the road like around curves, and bumps. Better to be on the safe side, but again, just my opinion.
So does that mean you divide GVW by 4?

Where does the safety margin come in?

Maybe I didn't understand your post.
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Old 10-20-2014, 08:37 PM   #63
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The 65 # on my 22' Bambi is the factory recomendation. The trailer weighs 3500 with a 1000# load factor. As moted above I will put higher preassue in when I embark for the West next Spring


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Old 10-20-2014, 09:19 PM   #64
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Hlamberton, are you sure you have 16" wheels rather than the factory equipped 15" wheels? You wouldn't want to put more than 65 psi in Good Year Marathon 15" ST tires.
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Old 10-20-2014, 11:33 PM   #65
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Hlamberton - before all the folks get carried away...

WELCOME to the forum.
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Old 10-21-2014, 06:31 AM   #66
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Yes, Hlamberton, glad to meet you and your new Bambi. Happy travels.

Now I have inter-ply shear to fret about along with axle spindle failures. I can understand multi axle trailer tires get side loaded a lot.

But when I zoom around in my pick up taking sharp corners with too much speed, I'm surely loading the side walls of my tires. CapriRacer certainly loads side walls on his race car. The LT tires on my triple axle Airstream sure seem strong.

I think I will use the dkottum theory: run'em and check-em.

David
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Old 10-21-2014, 08:04 AM   #67
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I wonder how that compares to Into-Wet-Intersection Skid from higher pressure /lower traction on the tire inflation danger chart.
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Old 10-21-2014, 09:24 AM   #68
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Yes, Hlamberton, glad to meet you and your new Bambi. Happy travels.

Now I have inter-ply shear to fret about along with axle spindle failures. I can understand multi axle trailer tires get side loaded a lot.

But when I zoom around in my pick up taking sharp corners with too much speed, I'm surely loading the side walls of my tires. CapriRacer certainly loads side walls on his race car. The LT tires on my triple axle Airstream sure seem strong.

I think I will use the dkottum theory: run'em and check-em.

David
I only brought up "Interply Shear" because that is the Science behind tread separations. Sorry but you do not put the same shear loads in your pick-up nor does Capri in his racer nor did I in my Camaro when setting records at 6 different road courses.
When a mortorized vehicle turns a corner all 4 tires are rotating around centers that point to the center of the turn radius (Sliding around corners when racing is different physics)
When you pull a tandem axle trailer around a corner it is impossible for the trailer tires to be rotating around center lines that point to the center of the radius. This results in significant side force and bending which leads to shear forces that are trying to tear the belts off the body of the tire.

In racing we may only get 100 to 200 miles use so there are simply not enough cycles to have the belts separate. Tire construction is also significantly different and if you do the calculations the load is about half what you would normally see if air pressure and tire size are taken into consideration. Not too many pot holes or curbs on race tracks either.
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Old 10-21-2014, 10:11 AM   #69
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We are the consumers trying to sort all this out.

Tireman, that makes sense but is rebutted by 2nd generation Airstream dealer Andrew Thomson who has equipped hundreds of Airstreams with Michelin LT tires set at lower pressures for gentler ride, better braking, and better wear for thousands of miles without reported failures of this type.

We are well aware of common tread separation failures on Good Year Marathon ST tires but none on 16" Michelin LT tires used at various pressures on our Airstreams. That is why we have chosen to use them., and most probably why Airstream is equipping large and premium models with them.

Somewhere we consumers have to find a truth in this apparent conflict in theory and practice.
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Old 10-21-2014, 11:27 AM   #70
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Low pressure compounds every other problem the tire may encounter.

The change from ST to LT means a trade off. I don't like pressures which seem too high either. On the other I may have spent more time on the side of the road than others. It isn't the delay or simply the expensive damage. It is also the very real danger of other traffic.

Granted my trailer brand isn't so affected by A-frame damage where truck suspension and hard tires seem to gang up. That it is a hard ride is part of still having a leaf spring suspension behind a 1T truck

There are two things I want. Reliable service and resistance to sway. A harder ride is the trade off.


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