Tire Grief

[neely butler]

I took the coach to a very good mechanic in Nashville (some 40 miles away)
and had all wheel bearings checked and re-packed, one was replaced. On the
way it had never drove or rode better, but after the work was done I had a
vibration like a wheel out of balance on the way home. Went straight to
local tire shop and had all six balanced, it was worse. The four rear tires
appeared to be very good (8.75--16.5 Michelin E-rate) but the two on front
were older with age cracks (Michelin D rated) so I decided to replace the
front ones. The ones on rear were not to be found. Several dealers checked
all their suppliers. That tire has been discontinued by Michelin. So I
bought two Firestones (8.75---16.5, E rated) for the front. Still have
vibration but not as bad. My thought, when the mechanic checked the rear
wheel bearings two wheels might have be place on the opposite side, causing
two to turn in reverse from original mounting. I had this happen once when
I had tires rotated on a car, wheels were turning opposite direction causing
vibration. Plan to leave Friday on long trip. Hate to have to endure this
vibration. Any suggestions??
Neely B. TN

 

[neely butler]

Tom,
The mechanic retired from GMC dealer in Nashville, has years of experience
on GMC motor-homes, works on them exclusively now at home, I believe he has
proper tools. I had him check all wheels, including front, he had to
replace one front bearing. Thanks
Neely B.
- -----Original Message-----
From: tom warner
To: gmcmotorhome
Date: Wednesday, May 10, 2000 3:43 PM
Subject: Re: GMC: Tire Grief

>When you say "all wheel bearings" do you mean also the front? If so how did
>he remove and replace them? Did he have the proper tool?
>

>>I took the coach to a very good mechanic in Nashville (some 40 miles away)
>>and had all wheel bearings checked and re-packed, one was replaced. On
the
>>way it had never drove or rode better, but after the work was done I had a
>>vibration like a wheel out of balance on the way home. Went straight to
>>local tire shop and had all six balanced, it was worse. The four rear
tires
>>appeared to be very good (8.75--16.5 Michelin E-rate) but the two on front
>>were older with age cracks (Michelin D rated) so I decided to replace the
>>front ones. The ones on rear were not to be found. Several dealers
checked
>>all their suppliers. That tire has been discontinued by Michelin. So I
>>bought two Firestones (8.75---16.5, E rated) for the front. Still have
>>vibration but not as bad. My thought, when the mechanic checked the rear
>>wheel bearings two wheels might have be place on the opposite side,
causing
>>two to turn in reverse from original mounting. I had this happen once
when
>>I had tires rotated on a car, wheels were turning opposite direction
causing
>>vibration. Plan to leave Friday on long trip. Hate to have to endure this
>>vibration. Any suggestions??
>>Neely B. TN
>>
>>
>>
>>
>

 

[g.m. hope]

Hi Neely,
I had a similar experience with tire rotation on my coach and on our family
car. I rotated the tires as is usually advised, switching positions but on
the same side of the vehicle. I had one tread separation and two blowouts
on the automobile within a couple of months following the rotation and
three blowouts on the motorhome over a somewhat longer period (didn't drive
it as much). I have become convinced that when tires are switched on the
same side of the vehicle, the reversed forces on the tread precipitate
separations leading to rough riding and, ultimately, blowouts. I don't
know what Xing the tires might have done - didn't run the control
experiment :^).
FWIW,
Marion Hope
77 Kingsley

>I took the coach to a very good mechanic in Nashville (some 40 miles away)
>and had all wheel bearings checked and re-packed, one was replaced. On the
>way it had never drove or rode better, but after the work was done I had a
>vibration like a wheel out of balance on the way home. Went straight to
>local tire shop and had all six balanced, it was worse. The four rear tires
>appeared to be very good (8.75--16.5 Michelin E-rate) but the two on front
>were older with age cracks (Michelin D rated) so I decided to replace the
>front ones. The ones on rear were not to be found. Several dealers checked
>all their suppliers. That tire has been discontinued by Michelin. So I
>bought two Firestones (8.75---16.5, E rated) for the front. Still have
>vibration but not as bad. My thought, when the mechanic checked the rear
>wheel bearings two wheels might have be place on the opposite side, causing
>two to turn in reverse from original mounting. I had this happen once when
>I had tires rotated on a car, wheels were turning opposite direction causing
>vibration. Plan to leave Friday on long trip. Hate to have to endure this
>vibration. Any suggestions??
>Neely B. TN

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
George M.(Marion) Hope, Ph.D.
1930 SW 19th Way gmhope
Gainesville, FL 32608 gmhope
(352) 371-2795 (Home) (352) 846-2111 (Office)

 

[neely butler]

Marion,
Thank you for your reply. I talked with the mechanic who did bearing work
and he declares that he put the wheels back just like they came off. We are
leaving for S. Carolina Fri AM. I will watch the tires very closely
Neely B
- -----Original Message-----
From: G.M. Hope
To: gmcmotorhome
Date: Wednesday, May 10, 2000 8:15 PM
Subject: Re: GMC: Tire Grief

>Hi Neely,
>I had a similar experience with tire rotation on my coach and on our family
>car. I rotated the tires as is usually advised, switching positions but on
>the same side of the vehicle. I had one tread separation and two blowouts
>on the automobile within a couple of months following the rotation and
>three blowouts on the motorhome over a somewhat longer period (didn't drive
>it as much). I have become convinced that when tires are switched on the
>same side of the vehicle, the reversed forces on the tread precipitate
>separations leading to rough riding and, ultimately, blowouts. I don't
>know what Xing the tires might have done - didn't run the control
>experiment :^).
>FWIW,
>Marion Hope
>77 Kingsley
>

>>I took the coach to a very good mechanic in Nashville (some 40 miles away)
>>and had all wheel bearings checked and re-packed, one was replaced. On
the
>>way it had never drove or rode better, but after the work was done I had a
>>vibration like a wheel out of balance on the way home. Went straight to
>>local tire shop and had all six balanced, it was worse. The four rear
tires
>>appeared to be very good (8.75--16.5 Michelin E-rate) but the two on front
>>were older with age cracks (Michelin D rated) so I decided to replace the
>>front ones. The ones on rear were not to be found. Several dealers
checked
>>all their suppliers. That tire has been discontinued by Michelin. So I
>>bought two Firestones (8.75---16.5, E rated) for the front. Still have
>>vibration but not as bad. My thought, when the mechanic checked the rear
>>wheel bearings two wheels might have be place on the opposite side,
causing
>>two to turn in reverse from original mounting. I had this happen once
when
>>I had tires rotated on a car, wheels were turning opposite direction
causing
>>vibration. Plan to leave Friday on long trip. Hate to have to endure this
>>vibration. Any suggestions??
>>Neely B. TN
>
>
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>George M.(Marion) Hope, Ph.D.
>1930 SW 19th Way gmhope
>Gainesville, FL 32608 gmhope
>(352) 371-2795 (Home) (352) 846-2111 (Office)
>

 

[g.m. hope]

>Marion -- I don't know if I'm missing something here but if you are switching
>tires on the same side of a GMC how are you getting reversed forces on the
>tread? For example, If you are moving a tire from the front wheel to a rear
>wheel on the same side, the tire is still rotating in the same direction and
>the forces on the tread would be the same wouldn't they?

Hi Emery,
If you think about it for a minute, the tire is, indeed, rotating in the
same direction but it is _pulling_ on the front (drive wheel) and being
"dragged" on the rear. Therefore, the forces against the tread (by the
pavement) are from rear to front on the front tire (as it pulls) and from
front to rear on the rear (as it is "dragged"). Another way (I find this
hard to describe in words :^) to look at it is that the pavement is pushing
the tread of the front, drive tire toward the front of the coach (or the
tire is pushing the pavement toward the rear) and the tread of the rear,
dragged, tire is being pushed toward the rear (pavement being pushed to the
front). The pushing is in different directions front and rear.

>Now, if you were doing this to a vehicle with duals and the outside of the
>tire was now facing in then the tread would be reversed but this doesn't
>happen on the GMC unless you cross the tire from one side to the other.

Correct and that is what I _didn't_ do.

>Years ago they warned about crossing radials but now they claim that it can be
> done. Nevertheless, I make a point to just keep them on the same side.
>I've found over the years that I've usually had to buy two tires at a time.
>It has been my practice over the years to buy new tires for the front, move
>those tires to the center and move those tires to the rear. I'll then keep
>the best of the two rear tires for the spare. The front tires usually wear
>at the "corners" due to the turning of the wheels and gradually moving them
>to the back has seemed to result in more wear out of the tires for me.

I wasn't really advocating doing anything in particular :^). I just ran
into this peculiar pattern of having 6 out of 10 tires blow or separate
shortly after rotating them (same side). I was concerned that Neely's
experience _may_ be an early indication of of the same sort of tread
separation/failure that I experienced - based on his concern that his tires
may have been switched around. Having six out of ten tires, with good
tread, on two vehicles dying within 300-500 miles of the rotations
convinced me that the rotation was the precipitating event. Whether the
cause was _actually_ the reversed forces is, of course, speculation - but
note that another netter indicates that manufacturers advise to rotate in
the X pattern to keep the forces in the same direction (I believe my
paraphrasing is accurate :^). As a result of my experience, I plan to let
the tires wear out in the position they start out in and replace them as
they do so. Wouldn't recommend that anyone else follow my lead though -
I'm still experimenting :^).

Since I haven't driven my coach in over 3 years, what I _really_ need to do
is rotate the tires around the _axles_ :^).

Cheers,
Marion
77 Kingsley

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
George M.(Marion) Hope, Ph.D.
1930 SW 19th Way gmhope
Gainesville, FL 32608 gmhope
(352) 371-2795 (Home) (352) 846-2111 (Office)

 

[henry davis]

>I hope I don't reach 3 years but it is possible since I only have one more
>year left. I won't have to rotate my tires either except for around the
>axles
>
>Scott
I don't know about that. Seems to me that you have the ultimate in rotation
flexibility. Come to think of it, you could even rotate the axles...

Henry

 

[henry davis]

>In a message dated 5/12/2000 1:12:15 AM Eastern Daylight Time,

>
> > Come to think of it, you could even rotate the axles...
>
>Very easily could rotate the axles, they are about 2" apart. Matter of
>fact--right where they were when you visited last year. If I did rotate them
>however I would have to put the emergency cables in from the back and rig up
>20' more of cables and pulleys. I would also have to change the brake shoes.
> Minor stuff compared to the whole scheme of things

Graingers has some nice air driven actuators. Just hook 'em up and do away
with the cables.

Henry

 

[emerystora]

> pavement) are from rear to front on the front tire (as it pulls) and from
> front to rear on the rear (as it is "dragged"). Another way (I find this
> hard to describe in words :^) to look at it is that the pavement is pushing
> the tread of the front, drive tire toward the front of the coach (or the
> tire is pushing the pavement toward the rear) and the tread of the rear,
> dragged, tire is being pushed toward the rear (pavement being pushed to the
> front). The pushing is in different directions front and rear.
> >>>>

Hi Marion -- This way of looking at it makes perfect sense now that you have
described it this way. I had never thought of this. I have never encountered a
problem over the years with moving my tires from the front toward the back,
though, so I don't know if this is what caused your problem or not.

As the rear tire rotates, it still seems that the weight of the motorhome would
tend to bend the tread in the same direction as the tread on the front wheels. It
would seem that the downward force of the vehicle weight would first press on the
rear edge of the tread segment and bend that segment forward as the tire rotates.
I can't think of a good way to simulate this but if you extend your fingers toward
the desktop and then rotate your hand in a forward direction while pressing
downward, your fingers will tend to bend toward the front. It would seem that a
free wheeling tire would do the same.

I think that I'll drop this subject because its really an area that I just don't
know enough about and I'll leave it to someone else who might have more knowledge
on this subject to expand on it if they wish, but I can see how you have viewed
it.

Emery Stora
77 Kingsley
Santa Fe, NM

 

[g.m. hope]

>I hope I don't reach 3 years but it is possible since I only have one more
>year left. I won't have to rotate my tires either except for around the
>axles
>
>Scott

Hi Scott,
I hope you don't reach 3 years too. . . .it's no fun watching your coach
going downhill in the driveway :^). I am starting to whip it into shape so
we can get those wheels rotating around the axles again :^).
Cheers,
Marion

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
George M.(Marion) Hope, Ph.D.
1930 SW 19th Way gmhope
Gainesville, FL 32608 gmhope
(352) 371-2795 (Home) (352) 846-2111 (Office)

 

[g.m. hope]

>Hi Marion -- This way of looking at it makes perfect sense now that you have
>described it this way. I had never thought of this. I have never
>encountered a
>problem over the years with moving my tires from the front toward the back,
>though, so I don't know if this is what caused your problem or not.
>
>As the rear tire rotates, it still seems that the weight of the motorhome
>would
>tend to bend the tread in the same direction as the tread on the front
>wheels. It
>would seem that the downward force of the vehicle weight would first press
>on the
>rear edge of the tread segment and bend that segment forward as the tire
>rotates.
>I can't think of a good way to simulate this but if you extend your
>fingers toward
>the desktop and then rotate your hand in a forward direction while pressing
>downward, your fingers will tend to bend toward the front. It would seem
>that a
>free wheeling tire would do the same.

I _think_ the condition you describe would be more like the driving wheel -
you are producing rotational energy with your hand/arm. . .but I may be
misinterpreting what you are describing. It's hard to translate this stuff
into words isn't it :^)? Interestingly, I think the situation probably
gets even more confusing when one considers what happens under breaking
:^). The forces reverse on the driven wheels under breaking but are
increased in the same direction when breaks are applied to the rears.

>I think that I'll drop this subject because its really an area that I just
>don't
>know enough about and I'll leave it to someone else who might have more
>knowledge
>on this subject to expand on it if they wish, but I can see how you have
>viewed
>it.

I think that's probably a good idea. I don't know anything about this
subject either -my comments were simply my interpretation of my own
experiences.

Cheers!
Marion

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
George M.(Marion) Hope, Ph.D.
1930 SW 19th Way gmhope
Gainesville, FL 32608 gmhope
(352) 371-2795 (Home) (352) 846-2111 (Office)

 

[g.m. hope]

>Hi Marion!
>Oh, I get it--- that is where the KYB shocks are going to be used. You are
>really going all out. I'll bet you $5.00 that you complete yours before I
>get mine done.

Actually, the shocks are part of the original problem that shut us
down. Two of the three blow-outs mentioned earlier occurred on a trip home
from GA. The first one took out the air hoses to my passenger side airbag,
ripped out the height adjusting valve and left me with no air suspension on
that side. I decided that if I dropped the other side and drove veeerrrry
slowly, I could negotiate the remaining 50 miles (this was before I learned
about Shrader valves). About half way, I noticed that I was beginning to
get some bumping that got progressively worse - but I made it
home. Figured I must had bent/broken something and screwed up the
suspension royally. A couple of hours after returning home, I heard a loud
thump outside but thought nothing of it. Next morning, I discovered that
another tire had blown - just sitting in the driveway - the separating
tread was what caused the bumping. However, I drove the final fifty miles
with the shocks supporting the rear of the coach and probably ruined them.

However, I won't take your bet :^). I _can_ drive my coach right now - it
would be a bit loud with two blown exhaust manifold gaskets and would use
up break pads rapidly because of a damaged rotor (break pad locked up
partially and welded the backing plate to the piston, causing big chunks to
break out of the rotor surface) . . . . but the coach is useable :^).

Cheers,
Marion
77 Kingsley - Semi-Crippled

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
George M.(Marion) Hope, Ph.D.
1930 SW 19th Way gmhope
Gainesville, FL 32608 gmhope
(352) 371-2795 (Home) (352) 846-2111 (Office)