Tire/Axle Question

Gdetrailer wrote:


Annd HERE is what Dexter says..

Page 77..


Click For Full-Size Image.

Snip...

Cupping can come from an out of balance issue or wheel bearing adjustment issue according to Dexter axles manual.


My tire shop tells me once they start wearing odd, nothing can slow it down or fix it other than replacing..

The chart shown above is a text book standard chart for tire wear. I do not disagree with any of it. However in this case, we are talking about a travel trailer made in the RV industry, not a car, truck etc. where that chart actually fits better. A tandem axle trailer made in the RV industry with no steering on the lowest budget that just gets by, is very different then an automobile with very good and stable suspension.

I do agree 110% with the statement about once a tire starts wearing bad, it will continue to wear that bad even after the problem is corrected. My step dad was in the garage business for over 40 years working on autos, and I can still hear him telling me that fact, that the tire wear will continue even if the issue was corrected.

Before we start telling Campermama that their wheel bearings are shot or set wrong causing the tire wear they are seeing, it might be better to first confirm that actual cupping as shown in that chart is root cause of the wear on the tires. There was going to be pictures posted so we can see what they are seeing. That can then help a lot better then speculating that cupping is actually happening. Maybe Campermama misdiagnosed the wear and called it cupping, now folks are telling them to fix cupping, fix the tire balance and wheel bearings.

I have measured axle alignment on several campers, corrected bent axle tubes, repaired incorrect hanger locations, and worn suspension to name a few of the issues creating tire wear on a travel trailer. While I have not done thousands of campers on alignment checks, out of all of the ones I did do, none of those tire wear issues were due to actual cupping of a tire due to a wheel bearing going bad or the tire being out of balance. I'm not saying those conditions cannot exist, but I would say it is highly unlikely given what we know so far.

The statement of, an out of balance tire issue causing tire cupping wear on a TT, let's think about that for a moment. Think about how many thousands of travel trailers and 5th wheels leave the factory every day with unbalanced brake drums and tires. Do they all have tire cupping?

If the wheel bearings where set wrong, having excess play, and there is 10K miles on the camper, odds are high, those bearings for 10K miles would be severally damaged to the point of total failure or close to it. Has anyone ever seen a documented trailer wheel bearing survive a bad setup that long?

And then what are the odds that bad bearings and out of balance wheels so bad to cause cupping, just happened to end up on the same axle tube, yet the axle tube next to it, does not have the issue?

With what little we know about this camper wheel alignment, actual tire cupping does not stand out as the root cause of the tire wear. If we can get some pics of all 4 tires, that may help a lot better then assuming cupping is the root cause.

Hope this helps

John

JBarca wrote:


The chart shown above is a text book standard chart for tire wear. I do not disagree with any of it. However in this case, we are talking about a travel trailer made in the RV industry, not a car, truck etc. where that chart actually fits better. A tandem axle trailer made in the RV industry with no steering on the lowest budget that just gets by, is very different then an automobile with very good and stable suspension.

I do agree 110% with the statement about once a tire starts wearing bad, it will continue to wear that bad even after the problem is corrected. My step dad was in the garage business for over 40 years working on autos, and I can still hear him telling me that fact, that the tire wear will continue even if the issue was corrected.

Before we start telling Campermama that their wheel bearings are shot or set wrong causing the tire wear they are seeing, it might be better to first confirm that actual cupping as shown in that chart is root cause of the wear on the tires. There was going to be pictures posted so we can see what they are seeing. That can then help a lot better then speculating that cupping is actually happening. Maybe Campermama misdiagnosed the wear and called it cupping, now folks are telling them to fix cupping, fix the tire balance and wheel bearings.

I have measured axle alignment on several campers, corrected bent axle tubes, repaired incorrect hanger locations, and worn suspension to name a few of the issues creating tire wear on a travel trailer. While I have not done thousands of campers on alignment checks, out of all of the ones I did do, none of those tire wear issues were due to actual cupping of a tire due to a wheel bearing going bad or the tire being out of balance. I'm not saying those conditions cannot exist, but I would say it is highly unlikely given what we know so far.

The statement of, an out of balance tire issue causing tire cupping wear on a TT, let's think about that for a moment. Think about how many thousands of travel trailers and 5th wheels leave the factory every day with unbalanced brake drums and tires. Do they all have tire cupping?

If the wheel bearings where set wrong, having excess play, and there is 10K miles on the camper, odds are high, those bearings for 10K miles would be severally damaged to the point of total failure or close to it. Has anyone ever seen a documented trailer wheel bearing survive a bad setup that long?

And then what are the odds that bad bearings and out of balance wheels so bad to cause cupping, just happened to end up on the same axle tube, yet the axle tube next to it, does not have the issue?

With what little we know about this camper wheel alignment, actual tire cupping does not stand out as the root cause of the tire wear. If we can get some pics of all 4 tires, that may help a lot better then assuming cupping is the root cause.

Hope this helps

John

John,

That chart CAME DIRECTLY FROM DEXTERS OWN MANUAL ON TRAILER AXLES.

Dexter builds trailer axles.

Dexter has plenty of paid "engineers" on staff.

Those "Engineers" most likely know more about trailer axles and tire wear on trailer axles than you or I.

Don't "shoot the messenger".

For the record, neither I OR Dexters manual stated anything about REPLACING BEARINGS..

Dexters manual mentioned bearing ADJUSTMENT which if for any reason the bearings are slightly too loose than allowable preload will allow the hub/wheel to wobble enough to cut in "cups".

Trailer axle bearings are not "factory sealed permanent bearings" which have no adjustments.. They are indeed "adjustable" and as they wear, they should be checked and adjusted as needed. As they are adjustable, it IS possible that they may have left the factory a bit on the loose side (not correct preload) and OP has put 10K miles on the trailer meaning it may be due to check and adjust the bearing preload.

The manual outlines the correct instructions for setting the bearing preload..

The manual also has a maintenance schedule chart that gives normal maintenance intervals for the bearings and other items which I suspect you and 99.9% of all trailer owners ignore..

It could also just be lousy tire build, and yes, this happens even to the supposed "best brands".. I had a set of trailer tires cup, replaced the tires, no more cupping..

But what really gets me is when folks start blaming it on "bent axles" or "axles out of alignment" as the very first thing to look at when the very first response is to check the simple things like tires being out of round or way out of balance and even checking the bearings preload settings. All things that do not cost a dime rather than making this an extreme sport of spending money.

Gdetrailer wrote:


John,

That chart CAME DIRECTLY FROM DEXTERS OWN MANUAL ON TRAILER AXLES.

Dexter builds trailer axles.

Snip..

Don't "shoot the messenger".

Snip..

The manual also has a maintenance schedule chart that gives normal maintenance intervals for the bearings and other items which I suspect you and 99.9% of all trailer owners ignore..

It could also just be lousy tire build, and yes, this happens even to the supposed "best brands".. I had a set of trailer tires cup, replaced the tires, no more cupping..

But what really gets me is when folks start blaming it on "bent axles" or "axles out of alignment" as the very first thing to look at when the very first response is to check the simple things like tires being out of round or way out of balance and even checking the bearings preload settings. All things that do not cost a dime rather than making this an extreme sport of spending money.

GD,

I have no beef with Dexter, I feel they are one of the top axle manufactures in the US trailer world. They have helped me greatly in the past with technical service. My beef, if there is one, is with the RV industry who allows welded on hangers to the frame not adhering to Dexter's recommended spec's. and shipping them. Dexter doesn't mention the screwup's the RV industry does to their products. There chart assumes the axles are installed correctly.

The original poster stated their tires are cupping. Do you have any evidence in what they have presented to date they understand what true cupping is? They may have picked a word they heard and thought it was the right one to use.

You picked my post to comment on that cupping can come from an out of balance or wheel bearing issue. And then you get into someone trying to explain about wheel alignment.

I was trying to help them understand that tire wear on a travel trailers comes from many different places, and we need more info to help them better understand what could be going on.

To your statement in blue on what you "suspect" I know or do with campers, don't go there. Leave it alone, you have no idea what I have done and can do in my shop.

And for the record, once we know more about the original posters tire wear, using a standard tape measure with some guidance, they can do some quick measurements across their tires so see if gross wheel alignment exists that can cause tire wear. Then they can figure out if they have the ability to correct the problem or need to find a shop who can. And yes, they can jack up the camper if they can, and feel for bearing wobble or do a tire spin test to look for an out of round conditions. It takes more work jacking up the camper then the tape measure checks. One just needs to understand what to look for when gross wheel alignment exists. And some of us are glad to help them with on how to do it.

Gdetrailes, stated. "Trailer axle bearings are not "factory sealed permanent bearings" which have no adjustments.. They are indeed "adjustable" and as they wear, they should be checked and adjusted as needed. As they are adjustable, it IS possible that they may have left the factory a bit on the loose side (not correct preload) and OP has put 10K miles on the trailer meaning it may be due to check and adjust the bearing preload."

If a properly adjusted tapered bearing has become loose, is should not be readjusted, as there will be metal missing from the bearing, making it non serviceable.

Richard

My travel trailer has Dexter tandem axles. I noticed both tires on the front axle have slight cupping on the outside of the tires.

Cupping on the tires outside/same axle on a trailer as others/Jbarca have said is most likely a toe/camber issue (bent axle) and easily fixed by a big rig trailer repair shop. They can tell you what is causing your tires wear issue.

Cupping across the tread is more indicative of a out of balance tire due to internal issues (partial tread delam/etc).