What pressure do you use 16" Michelin?

[Tireman9]

Originally Posted by dkottum

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

[Tireman9]

Originally Posted by SteveH

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.

[Hlamberton]

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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[dkottum]

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.

[mefly2]

Hlamberton - before all the folks get carried away...

WELCOME to the forum.

[dbj216]

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

[dkottum]

I wonder how that compares to Into-Wet-Intersection Skid from higher pressure /lower traction on the tire inflation danger chart.

[Tireman9]

Originally Posted by dbj216

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.

[dkottum]

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.

[slowmover]

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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[dkottum]

Slow'

We've traveled 1200 miles so far on Michelin 16" this trip with 65 psi, the last 250 on I40 with plenty of semi's. 2012 Ram 1500 full coil springs 120" wheelbase and ProPride hitch.

Excellent weather, little crosswind but semi's passing have no push and there is no sway felt at this point. That is a small sampling, adding to what others have reported, but I believe we may have resistance to sway, reliable service, and a soft ride in our sights unless there is a change in our "good luck".

I will report as we move along.

[CapriRacer]

Originally Posted by dkottum

We are the consumers trying to sort all this out........

It's very complex and it's easy to get lost in the details.

Originally Posted by dkottum

...........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......

Correct me if I am wrong, but isn't everyone is replacing 15" Goodyear Marathons with 16" Michelins or ST235/80R16's with LT235/85R16's - both of which are increases in tire size - and directionally that is the right way to go for durability improvements. In some respects this is more a comment about the sizing of the tires and not the brand.

[r carl]

Originally Posted by CapriRacer

It's very complex and it's easy to get lost in the details.



Correct me if I am wrong, but isn't everyone is replacing 15" Goodyear Marathons with 16" Michelins or ST235/80R16's with LT235/85R16's - both of which are increases in tire size - and directionally that is the right way to go for durability improvements. In some respects this is more a comment about the sizing of the tires and not the brand.

Are you defending st tires?

[SteveH]

Originally Posted by CapriRacer

Correct me if I am wrong, but isn't everyone is replacing 15" Goodyear Marathons with 16" Michelins or ST235/80R16's with LT235/85R16's - both of which are increases in tire size - and directionally that is the right way to go for durability improvements. In some respects this is more a comment about the sizing of the tires and not the brand.

Actually, no. Most are replacing ST225/75R15D's with LT225/7516E's

[SteveH]

I know of no Airstream trailers that can fit ST235/80R16's or LT235/85R16's.

[dbj216]

dkottum asks what other Airstreamers are running for tire pressure with their 16" LT tires. The max pressure at 80 psi makes for a pretty bouncy ride for our trailers. We used to say if you want your one ton pick up to ride smoother, put a ton of weight in the bed. These trucks are pretty bouncy unloaded. So we would reduce tire pressures to soften the ride when unloaded.

I can only imagine all the factors that go into a tire pressure selection for a trailer. I suspected Ford Explorers rolled over years ago due to low tire pressure (lack of maintenance by the owners.) I felt the same with GYM ST 15". I ran GYM 15" ST load C tires for five years without problems. I wonder what the actual failure rate percentage of total was for those tires? I see ST tires on nearly all the trailers I look at, e.g. hard working utility trailers with skid steers on them. ST trailer tires can't be all that bad.

But dkottum asks, and I'm listening, what other Airstreamers are running for tire pressures, and what problems might be happening. Anecdotal experiences can be helpful. "The truth is more important than the facts".

So based on this thread I am more comfortable running 65 psi in my LT 16" Es. I've got 4000 miles on them with no problems.

David

[Jim Flower]

I am running at 76 lbs in my LT225r16 Michelins. They currently have 78,000 k on them. I had the axel aligned last week because 1 tire was wearing on the outside edge. There is no logic behind the 76 lbs except that it works for me and it is easy to remember because the Airstream rolls at 7600 lbs and I adjust the pressure upwards by a lb or two when heading out for a longer trip and my wife has the thing loaded with all her junk. I don't have any junk. Jim


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[dkottum]

Some time ago there was a thread and poll here comparing the failure rate of various trailer tires. There were no failures reported on Michelin 16" LT used on Airstreams. The original GYM's were much worse as I recall.

Nobody likes flat tires so that inspired me to make the switch to Michelin 16"s as well. Now if we could find a good overall tire pressure to use based on members' experiences, that is, actual use on Airstreams. So far it looks like the range of 65 to 80 psi is working well.

We paid a bundle for this Airstream so I want to take care of it, I don't want to wreck it or shake it to pieces. For our FC 25 carrying 6520# on the axles when attached with weight distribution applied, using LT tire load chart it looks like 65 psi allows 15% for variations and another 10% of that for grins so that's what we are using.

So far it handles without fault, and the ride feels less harsh from the driver's seat than at 80 psi. As for sway or semi push we don't have any, it's the same as with 80 psi. We use a Hensley/Propride style hitch and that is significant here.

Am hoping to get more actual pressure and experiences noted by those using 16" Michelins on their Airstreams.

We're touring some Presidential Libraries this trip, very interesting look at American history. Lincoln last week, Clinton in Little Rock today.

[Tireman9]

Originally Posted by dkottum

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.

Given the current state of affairs in the rest of the RV trailer market where low cost components is the majority ( not so much in the premium Airstream market) where low price is the primary requirement to make a sale of tires to the RV assembler, I am not surprised that the response is different here than on other forums. BUT you should not confuse the results of ST type tires with those of LT type tires.

It is apparent that Airstream has designed some of their trailers to allow for lighter weight units (no slide-outs etc) but also to allow room for larger LT type tires. If you want to use LT rather than ST type tires you will need larger size tires or significantly higher tire pressure. I specifically wrote about how to do this switch on July 15 2014 in my blog.

If you apply a sufficiently large tire the forces that cause failures will be lower than when you use the smaller tire that has a lower margin of safety.

I'm not sure how to answer questions about what inflation to run without offering "best practice" advise.

Now I'm glad to hear that your dealer has never sold a unit that suffered a tread separation tire failure. Maybe the answer is for everyone to simply buy from him and not worry about inflation levels and to ignore advise based on engineering principles. (end of sarcasm)

Seriously though, I would like fellow RV owners to have fewer tire problems. That is why I write a blog just on RV tire applications and why I give free seminars on the topic and why I post to 11 different forums.

So how would you answer the question on what is the proper inflation to run on all Airstream trailers? and Why?

[Ag&Au]

What pressure do you use 16" Michelin

All the facts, truths, and even questionable anecdotes are interesting, but in no way transferable from one trailer/tow vehicle combination to another, and perhaps even from one day to another on the same setup. So although, these numbers are interesting to know as a comparison to your own practices, they cannot be interpolated or extrapolated for your own use.

This is my opinion and I'm sticking to it right or wrong:
The only sure way to arrive at the optimum pressure is to first know how much your trailer weighs in its current configuration (attached with weight distribution set) to the tow vehicle. Take that weight and divide it by the number of tires (presumably, you have taken care to load the trailer reasonably balanced). Increase that weight by the 15% factor "Capri racer" recommends because you are using truck tires on a trailer. Then take that resulting weight to the tire manufacturer's load/pressure table to find the proper inflation pressure. If your adjusted weight is more than the table covers, then don't carry that much weight or get bigger tires.

This is in my mind the most important of all:

Then on any given trip, monitor the pressure and temperature with a TPMS to ensure you are staying within the limits recommended by those here that know more than I. I do this step. The first part above , I do to some degree. The monitoring to me is the most important, because it will tell you that you didn't do the calculating part correctly, before there is failure.

Ken

P.S. as far as beating up the trailer is concerned:
The only time I have experienced that is when the road has been so rough that I do not believe lower tire pressure would have done any good at all.