front tire wear

[Doug Allman]

Have had these Michelins on since we bought coach in 2012 and now have approx 53,000 miles on.
Both of the front steers have developed a wear pattern along the outside 3/8" of the shoulder. It is like a convex strip along the outer edge of the tire and very uniform all the way around on both tires. Just a smooth dip all the way around. There is no noticeable pull on the steering wheel.
It is either caster or camber I believe but I do not know very much in regard to this subject. I would not think it was alignment but I could be mistaken. Maybe they are toed in too much.
I ask because I have no idea of whom in my local area is credible to make the proper adjustments and would like to have an idea of what they should be doing when i find someone to service.
Before I do have any work done on the coach I am going to move the tags to the steers.
Any help is appreciated.

[Edward Buker]

Doug,

I had removed a set of Michelin XZA2 Energy tires from our 2002 Marquis after 5 years of service and about 40K miles. I noticed that the outer edges of the fronts, both inner and outer edges, were worn more then the remaining tread. Seems like it was about half of the width of the outer most tread pattern before you reached the first groove had some accelerated wear. The coach tracks and handles so well that I did not want anyone to make any changes. Given it was on both fronts, both edges, and quite symmetrical, I was more thinking it was more related to Michelin's tire design then to the coaches alignment but I was not sure. Your issue sounds very similar.

Later Ed

[Steve Huber Co-Admin]

Doug,
I'm far from a tire expert but wear on both shoulders is usually caused by under inflation. Caster, camber. toe in etc. will normally cause wear on one or the other shoulder but not both.
http://www.bridgestonetire.com/tread-and-trend/drivers-ed/tire-tread-wear-causes
Steve
Semper Fi!

[Doug Allman]

Ed, Steve,
I used to keep at 120 lbs and then went to 110 lbs after I read about weight and tire pressure requirements. Have weight readings on all tires & axles separate on coach.
Maybe I will just go back to the 120 lbs when I move tags up front because if I remember right I did not see this wear until after I changed the pressure before we left last September for Branson.
Take a look after 4000 miles or so when we get into Yuma 1st of October.     Thanks for your input.

[Gerald Farris]

There are basically three angles that encompass a front end alignment. Caster is the tilt of the steering axis (king pins) forward or backward and it does not cause tire wear under normal conditions. The caster angle on a Beaver is not individually adjustable without bending the axle, so it is rarely changed as part of an alignment. Caster is sometimes adjusted on both front together by using tapered shims between the axle and it's mounting to change handling characteristics.

Camber is the tilt of the steering axis in or out at the top. This angle can cause tire wear if it is excessive, but adjusting it on a Beaver requires bending the axle, so it is also rarely adjusted. Worn king pins can cause a negative camber condition (leans in at the top) that will wear the inside of the tire, but the worn parts are replaced instead of bending the axle.

Toe in is a self explanatory angle, and it is normally the only adjustment made on a coach front end alignment. It can wear the inside or outside of a tire, but not both at the same time. So if tires are wearing on both shoulders at the same time, it is either a tire construction characteristic or an overweight/underinflated condition. 

Gerald       

[Doug Allman]

Gerald, If it is only on the outside shoulder of each steer and they both look identical is underinflation the culprit?

[steve zannella]

Doug

I had the same problem with my Michelin XZA2 Energy tires bought new in 2010 both outside edges were abnormally worn on both front tires. The wear pattern was weird it looked like a 30 degree wear edge  1/2 inch into the tire.

Can't imagine how they could wear that way, the rest of the tire showed no abnormal wear only on the outside edges.

Replaced the Michelins with Toyos no abnormal wear pattern same alignment.

[Joel Ashley]

Doug I think there was some confusion along the way of this thread;  you did indeed state right off that it was outside wear, but outer edge of the shoulder could be also interpreted as either or both sides of one tire.  Given what Gerald capably explained, your symptoms would seem to imply toe-in as the issue.

If you are anywhere near Grants Pass this summer, Henderson's Line Up has pretty good equipment and ability in anything chassis, and most certainly alignment.

-Joel

[Edward Buker]

I had the coach weighed all 4 corners and then ran the tire pressure +5 to 10lbs over the recommended value of the axle tire position that had the most weight. The fronts were very close in weight by the scale while the rears were significantly heavier on the driver side. So I am sure that the inflation was as intended. I believe this is a characteristic of the tire design best I can tell. The tire edges may obtain more stress and pressure while turning and wear more aggressively then the center region.

Gerald thanks for the tutorial on alignment as it relates to our coach front ends and the issues poor alignment can cause.

Doug, when I read your post I thought you were referring to both edges. Joel picked up on that.

Steve, it sounds like your Mich. tires wore like mine did. There is more flex in the sidewall on the Michelins XZA2 Energy tires then there is on the Toyos. Maybe that characteristic has something to do with the wear pattern.

Later Ed

[Doug Allman]

As Gerald and others have said many times "you need to give us all the information". I apologize.

I have Michelin XZE2+ tires. Before we left Costa Mesa after purchase I had the 10 year old Goodyears taken off and Michelins put on. They could not get the energy tires but they had these in stock so we decided not to wait a week and had them installed. They called them a City Bus tire as they have a much heavier sidewall for scrubbing on curbs.
May or may not be tire problem I am having but in 2-3 years at most they will be replaced with the current Michelin energy tires. I got 3 years on these steers with no noticeable wear and so the tags moved up front will get me 3 more and then all gone.
Appreciate all's input.

[Karl Welhart]

This type of front tire wear has been discussed for many years on many different RV forums.  The best argument I have heard was from a Goodyear tire engineer at a motorsports event in 2010. 

His characterization was very simple and direct.  These tires (22.5") were designed for OTR trucks NOT motorhomes.  The motorhome load dynamics of the front tires during normal driving is very different than on a truck.  This very different load dynamic causes this wear we are seeing on these tires. 

Goodyear redesigned their RV specific tires just to deal with this type of wear characteristics.  Other tire manufacturers have also made core design changes to deal with this issue and others have not. 

Bottom line, this unusual wear pattern is normal for motorhome type vehicles and may or may not be a concern issue for the integrity of the tire.  Alignment changes will not help or change this wear pattern.

I think in the case for Goodyear, it was a major reason for concern.  That is why they redesigned their RV specific tires...

[Joel Ashley]

I encountered the same scenario regarding Toyo's, Karl.  Owners and dealers experienced similar wear on motorhomes because the tire was made for trucks.  Toyo took it to heart that there was a viable RV market out there that was misapplying their truck tire, so they first notified dealers to stop putting the tire on motorhomes.  Then they used different materials and designed a whole new, motorhome-specific tire.  Unfortunately they're still coping with the bad rap from the predecessor's history on RV's.

Joel