Tires for 1987 34W, original aluminum rims... suggestions?

[Tireman9]

Tires can "self align" their toe when set to 1/16" to 1/8" toe-in depending on the bushing clearances.
My previous comments were aimed at tandem axle trailers that need to have the two or three axles all parallel.

Sounds like any trailer with the suspension set-up you outlined have no excuse to be out of spec for any of the tires.

IMO out of align tires will increase the side load (cornering load) which in turn increases the Interply shear which can eventually lead to belt separations in ANY brand tire.

[Razorback]

Here is a good picture of the Adjust-a-Ride suspension that was described:



And a good real-world picture:

[silverloaf]

Tireman9-

Thank you for the response. Regarding tire pressure when using LR-E tires, I talked with Carlisle Tech Support about running them at lower pressure than what's molded in the side wall. He claims that lowering the pressure to say, 65psi, makes the tire think it's overloaded.

I presume he's implying the tire is being exposed to at, or near, it's max load capacity. Is there any correlation between tire pressure and load capacity of a tire? Are 10 ply tires (like my LR-E's) more vulnerable to excessive heat at the shoulder just because the walls are thicker?


Thanks.

[silverloaf]

Paul - That's a very good picture.

It was rather daunting when I first took the suspension apart for repair and upgrade. Low ground clearance didn't help either. But it is a rather impressive system for a travel trailer, including the use of shock absorbers for each axle.

My biggest challenge was torqing the shoulder bolts at each pivot point to 125 lb ft. There isn't much tool clearance with a 16" long torque wrench. I could have benefited from a tummy-tuck.....

[Razorback]

Hi, Bob.

Yes, I really like that suspension system. I got to really look at mine after we got home from our first trip after the previous set of tires were installed (and one of our longer yearly trips). Noticed the rear curb-side tire had worn considerably . Figured out that the axle needed to be adjusted.... the leading edge of that tire was toed out. Like you, the biggest challenge was getting the trailer up and having room to work. Got it done, though.

It’s a pretty simple system that provides nice adjustment.

On our 1987 Avion, I seem to remember that it has 3 available holes to anchor each axle at the center, compared to the 2 shown in the picture I had found of that area.

[silverloaf]

Paul,

I believe there is a hole above the one being used. I think it's out of camera view or obstructed by the belly pan.

I also believe the center hole in the bracket is the factory setting for the axles. I'm not sure why anyone would use the other holes unless they were trying to compensate for road damage, overload or weak (or really over-stiff) leaf springs.

Your thoughts?

[Tireman9]

Not sure of the best way to respond to a specific question on this Forum as I don't see a "Quote" option. BUT

RE Silverleaf comments "Carlisle Tech Support about running them at lower pressure than what's molded in the side wall. He claims that lowering the pressure to say, 65psi, makes the tire think it's overloaded."
Don't know a tire with say 1500# actual load on it could "think" it had 1,800# load on it.

"Is there any correlation between tire pressure and load capacity of a tire? Are 10 ply tires (like my LR-E's) more vulnerable to excessive heat at the shoulder just because the walls are thicker?"

There is a absolute correlation between load capacity and inflation. Just look at any Load/inflation table published by any tire company. It is the air pressure that supports the load not the tire rubber.

Yes, some tires can generate more heat than others if they have thicker rubber but LR-E tires do not always have thicker sidewalls. Sometimes engineers can achieve the higher Load Range with just more strands of steel in the belt or in one case I personally know of ...with an increase in the number of strands of wire in the bead.

Please do not confuse the old "ply" with current Load Range. While it may be easier to think in terms of ply tires haven't had the stated number of ply since the 50's or 60's. Read the tire sidewall to learn tha actual material in your tire.

It is acceptable to run less than the maximum load in a tire and to match the inflation found in the tables with the actual load.

Have to wonder what the background is for the Tech Support person. Sometimes I think they are interns who are given a book of standard answers who sometimes invent the answer as they have no working knowledge of how to design a tire.

[silverloaf]

Tireman9 -

Thank you for the response.

However, my intention was not to throw the Tech Support person under the bus. It was a conversation, not a quote; hence, no quotation marks.

If he didn't have enough information to be more techincally astute, chance are product design engineering only gave him cannon fodder to work with. Been there...seen that.

[Razorback]

I was mowing the yard today and thought I would take a picture of the scrub made by the tires on our Avion. This happens when we are getting ready to leave.... I have to pull the Avion out of it’s parking spot, do a 180, and head for the double gate. Those tracks are made by the inside set of tires as they are being dragged in a left-hand turn to head for the gate. I think the main scrub is made by the front left tire.

Gives you some idea of just how much scrubbing is happening in a tight turn.

[Tireman9]

Yes the scrub pattern is what triggered my investigation into the Interply Shear on trailer tire applications.

Tires are not rotating around a centerline that goes through the center of the turn radius. The dragging is what generated the high belt forces.
Good news is that on grass the tires slip and just tear up the grass. On paved roads, the tires do not slip as much but deflect as seen here
https://youtu.be/gqDesPT9eF4