[ccjohnson]

               
I have attached pics of steer & tag tires we just replaced a while back.  Hoping for some insight as to what causes this. No one at tire shop has had satisfactory explanation so far. I do have a theory!  A bit of history; When we first picked up coach 6 yrs ago we blew a drive tire on the way home.  Fran's brother suggested we get 2 new steer tires for remainder of trip home instead of just one  drive tire. At 10 pm outside of Ozona,TX  all I could get were Bridgestone load range G max inflation 105 psi.  We ran these for 3 1/2 - 4 yrs.  had some "cupping" on steer tires.  The drive & tag tires I put on coach were load range H max 120 psi drive tires.   On the way to Quartzite  1 1/2 yrs ago we again blew a drive tire. We got 8 new load range G max pressure 100 psi (they did not have H available).  My "oilfield" mentality of just run it until it is really broken had kicked in.  After all we had done well with G's on steer axle for 4 yrs.  After 1 1/2 years the "cupping & wear on steer tires was becoming severe.  Tags were wearing a little strange also but not as severe. Drives were wearing perfectly.  I rotated tags & steer tires in hopes of extending life.  Not a great deal of success. after +/- 3K miles driving slow (50-55 mph) on "square" tires, I ordered 4 Yokohama load range H max pressure 120 psi. After +/- 3K miles no strange wear on them and steering/handling has much improved. Running steers at 120 psi.  I pulled up a weght ticket from last time we had weighed coach: 14,400 steer, 20040 drives, tag 8080.  Checked Yokahama web site for recommended load ranges & pressures.  Looks like I have been blessed to not have had extreme failure issues on severely over loaded steer tires all these years. My theory on wear is that extremely overloaded and under-inflated (for the weight) combined with extremely hot roads ( we did a lot of AZ-CA dessert this year) caused the tires to "scrub" on cornering which resulted in strange patterns.    Would appreciate any additional thoughts.
ps: Newell tag on inside: steers 120 psi, drives 100 psi, tags 110 psi.  I will run at these pressure from now on.  Will replace G drives with H in about 1 1/2 yrs.

[Richard]

Cliff,

If you aren't putting us on, then I would say that the tires in the picture exhibit decomposition of the rubber, and not wear pattern. What caused the decomp? Could be extremely high temperature cycles or exposure to ozone or chemicals.

Have you driven the coach on any surfaces that could have been contaminated? Oilfields? Frack sites?

This is just my opinion and probably wrong.

[jcus]

Have to agree with Richard. If you had bought all at the same time, would have though bad mix at factory.
But have to think there must be some sort of chemical reaction with the rubber. Some rural counties still spray
their back roads with used engine oil. Maybe something nasty mixed in with it, and you drove through it.
Jim

[ccjohnson]

I did notice some "granulating" on one tire before replacing it. Had been running about 70 mph for around 60 miles in a hurry from Kingman to Phoenix with ambient temp +/- 118F. At that point when I noticed the 'granulating upon arrival I slowed down to 55 max until replacing tires. I agree heat was major factor, but chemical issues from road do not explain why drives have normal wear. They travel on same surfaces. At 20K wt on drive duals they would also not be severely overloaded. Tommy Key has always encouraged me to run H on at least steer if not all axles. I will definitely be following that advice from here on. Also I don't feel the ' road wandering" as before on load range G steers. Much easier to keep in a straight line now.

[Fulltiming]

Clint, I don't drive quite that fast, usually 65-68, and will slow down to about 60-62 in really high temps (over 105F) and I have always run 11R24.5 H rated tires and most of the time run 305/75R24.5 Michelins on the front that are J rated. Of course I am not racing from job site to job site either. I have never seen tires do that. I do check the tire temperatures with an infrared thermometer at rest stops to insure there is nothing out of whack. The side facing the sun is always 10-20 degrees hotter than the other side. It does look like the rubber actually melted (either from heat or from chemical reaction). Certainly doesn't look like any alignment wear I have ever seen.

[ccjohnson]

For the record, these are Regul tires. That is all that was available as a full set at the time. I believe they are manufactured by Samsun in China.

[Richard]

Gee this is very weird, when I look again, I see something I didn't see the first time. If you look carefully at the smooth section of the tire close to either edge you can plainly see the tiny sipes cut into the last tread block on either side of the tire. The rubber around that section looks like what a normal tire should look like. On second look, it is almost like the tire was rolled into gummy rubber that stuck to the tread. And that gummy stuff kind of eroded away. I have no idea what would cause this.

Clint, the story about the tire history is hard for me to sort out. So let's stick with these tires for sec. These are tag and steer tires put on at the same time. How many miles did they have on them? How old? How long did it take for this condition to develop?

Are the drive tires the same brand and age? What to they look like?

[ccjohnson]

The tires in pics were steer tires and tag tires. The drives I still have on are same and were installed at the same time and are wearing smoothly and evenly. I had rotated the really squiggly ones from steer to tag for last +/- 3K miles. Tires are about 1 1/2 years old with +/- 26K miles on them. Cupping became noticeable at about 9 months to a year in. However, it appeared to be about the same as on my 1st set on Bridgestone steer tires (also load range G). After running this summer in really hot weather the wear became much more aggressive and noticeable. That is when I rotated them. Wear patterns did not seem to improve so I just replaced them with the new load range H Yokahama's.

[jcus]

Pretty hard to imagine, but take an old slick tire put a layer of soft rubber on it, then put it in a mold to 
put a tread in it.

[77newell]

You seem to have the most extreme case of rivering I've ever seen on steer tires. Overloaded tires will experience both overheating and rippling of the outside edge of the tires. High speed will make this worse. Once the rippling gets established in the wear pattern it becomes a self sustaining pattern that progressively worsens. Steer tires are highly prone to rivering (rippling on the outer edges) and that has lead to the development of steer tires with a unique tire edge design.

The solution is properly rated tires, properly inflated for the load, plus at higher speeds many makers require even higher pressure by 10psi or so.