dw@rocksvax.UUCP (Don Wegeng) (01/26/85)
The Service manager at my Saab dealer recently told me about an
abnormal tire wear problem that they have been seeing on quite a few
cars (including mine). It seems that the rear tires have been
experiencing a wear pattern which consists of one or more bands
which are about one inch wide and run at a 45 degree angle across
the tire. The problem is much more pronounced on tired which have
not been rotated (front to back and vice versa).
Saab is not sure about what is causing the problem. At first
they thought the tires were at fault, but this has been proven
false. Now they suspect that there may be some kind of resonance
which is causing the problem. They also think that the amount
of tow-in that these wheels posess may affect the problem.
Saab currently suggests that owners rotate their tires every 7500
miles. They say that any abmormal wear that a tire experiences
when on the rear will be corrected after it is used on the front
for awhile. They also suggest that customers who have experienced
this problem should have the tow-in adjusted.
Saab (with the dealers) is compensating customers who have
experienced this problem by discounting the purchase price of
new tires by the expected remaining miles on the worn tires. I
was able to purchase two new Pirelli P8's for the price of one,
not bad considering that the car has been out of warrenty for over
a year.
Incidently, my Service Manager says that he has seen this problem
on other front wheel cars (he mentioned Volkswagons, but didn't
specify a model). Has anyone else heard of this? (My car is a
1983 900S with 30K miles)
--
/Don
"Don't touch me, I'm a real live wire. Psycho Killer..."
arpa: Wegeng.Henr@Xerox.ARPA
uucp: {allegra,princeton,decvax!rochester,amd,sunybcs}!rocksvax!dw
|| ihnp4!tropix!ritcv!rocksvax!dwdlp@akgua.UUCP (D.L. Philen [Dan]) (01/29/85)
The rationalle for rotating radial tyres on the same side of
the car and NOT from corner to corner is the following:
Radial tyres have belts of steel (usually) instead of strands
of cords. The belts thus take up a "set" when put on
the car and run for awhile. Rotating front to rear but NOT
corner to corner ie right front to left rear assures that the
tyres always roll the same direction. If you rotate corner
to corner the tyre is reversed on the car and in effect rolls
backward against the "set" of the belts. This increases
wear because the tyre is not used to rolling that way.
Does all this make sense.
Contrary to popular belief, Lucas was not the inventor of darkness.
Q. Do you know why the English drink warm beer?
A. They have Lucas refrigerators.
Dan Philen akgua!dlpdswankii@uok.UUCP (01/30/85)
Radial tires seen to "learn" which way they are rolling. After they "set" into a particular direction, making them roll the other direction can cause the tread to separate from the carcass of the tire. David Swank II University of Oklahoma ctax!uokvax!uok!dswankii
dhd@hou4b.UUCP (D.H.Dawdy) (01/30/85)
A friend of mine had this problem once; every time he let the clutch out (like at a stop sign or at a traffic light) the rear tires made noise and he said there was a strange odor that usually followed. He took the car back to the dealer who offered to keep the car for a week and test it every day to see if the problem might go away on its own. The dealer also suggested it might be related to the gas he was using and said a tune-up might fix it; he wasn't sure. My friend decided not to give up the car for a week or gamble on a tune up price from the dealer. He did decide, though, to try tuning it up himself. After changing the timing radically and covering all the air inlets to the carburetor the problem almost went away; the tires still made noise when he let the clutch out but the smell was almost completely gone. He eventually got rid of the car because he was replacing rear tires every two months.
2141smh@aluxe.UUCP (S. M. Henning,) (01/31/85)
**** **** From the keys of Steve Henning, AT&T Bell Labs, Reading, PA aluxe!2141smh > ... The belts thus take up a "set" when put on > the car and run for awhile. ... If you rotate corner > to corner the tyre is reversed on the car and in effect rolls > backward against the "set" of the belts. This increases > wear because the tyre is not used to rolling that way. COROLLARY: Never backup when using steel belted radial tires.
hansen@utah-gr.UUCP (Chuck Hansen) (01/31/85)
I've always been under the assumption that the 'same side' rotation for radials was to keep the tread from separating ... anyway, I've always abided by the story. Chuck Hansen
ix1037@sdcc6.UUCP (Christopher Latham) (02/01/85)
> > The rationalle for rotating radial tyres on the same side of > the car and NOT from corner to corner is the following: > Radial tyres have belts of steel (usually) instead of strands > of cords. The belts thus take up a "set" when put on > the car and run for awhile. Rotating front to rear but NOT > corner to corner ie right front to left rear assures that the > tyres always roll the same direction. If you rotate corner > to corner the tyre is reversed on the car and in effect rolls > backward against the "set" of the belts. This increases > wear because the tyre is not used to rolling that way. > Does all this make sense. > > > Dan Philen akgua!dlp This is all well and good but Michelin makes no claims that their radial tires must be kept on one side of the car once mounted on that side. Christopher Latham U.C.San Diego Dept. of Applied Mechanics and Engineering Sciences ..sdcsvax!sdcc6!ix1037
dw@rocksvax.UUCP (Don Wegeng) (02/02/85)
In article <4928@fortune.UUCP> marsano@fortune.UUCP (Derek Marsano) writes: >About your Saab whose rear tires are wearing abnormally: > >I once heard that radial tires should be rotated front to >back on the SAME side of the car. > >How have your tires been rotated? More generally, can >anyone confirm or deny this advice on rotation of radial >tires? Radial tires should be rotated front to back on the same side of the car, according to my Saab dealer. As for my tires, I did not rotate them at all (I know, I'm stupid). As I stated in my original message, Saab says that rotating the tires every 7500 miles or so will take care of the problem. -- /Don "Don't touch me, I'm a real live wire. Psycho Killer..." arpa: Wegeng.Henr@Xerox.ARPA uucp: {allegra,princeton,decvax!rochester,amd,sunybcs}!rocksvax!dw || ihnp4!tropix!ritcv!rocksvax!dw
knight@nmtvax.UUCP (02/04/85)
In article <> dhd@hou4b.UUCP writes: >A friend of mine had this problem once; >every time he let the clutch out (like at a stop sign or at >a traffic light) the rear tires made noise and >he said there was a strange odor that usually followed. > >He took the car back to the dealer who offered to >keep the car for a week and test it every day to >see if the problem might go away on its own. >The dealer also suggested it might be related to the >gas he was using and said a tune-up might fix it; >he wasn't sure. > >My friend decided not to give up the car for a week or >gamble on a tune up price from the dealer. >He did decide, though, to try tuning it up himself. >After changing the timing radically and covering all >the air inlets to the carburetor the problem almost went >away; the tires still made noise when he let the clutch out >but the smell was almost completely gone. > >He eventually got rid of the car because he was replacing >rear tires every two months. Sounds like the dealer was primed to do the classic "we're almost sure we know how to fix it" consumer ripoff and funnel your friend's money into a black hole. Sounds like your friend made the right decision in time. My only question is, what kind of car was it? Bob
hav@dual.UUCP (Helen Anne Vigneau) (02/06/85)
<*munch*>
=> Radial tires seen to "learn" which way they are rolling. After they "set"
=> into a particular direction, making them roll the other direction can
=> cause the tread to separate from the carcass of the tire.
=> David Swank II
=> University of Oklahoma
=> ctax!uokvax!uok!dswankii
Radials can also be rotated side-to-side, but it ain't easy. You have to
take the tire off the rim, turn the *rim* around, and replace the assembly on
the car, making certain that the *old* forward direction *remains* the
forward direction. Let me see if I can diagram this:
front of car
___________________
| |
_ _
Tire 1 ( ) <- tires -> ( ) Tire 2
Rim 1 - - Rim 2
| |
| |
| |
| |
| |
_ _
Tire 3 ( ) <- tires -> ( ) Tire 4
Rim 3 - - Rim 4
| |
-------------------
rear of car
Without changing the forward orientation of any of the tires, Tire 1 would be
mounted on Rim 2 or 4 and replaced on the *right* side of the car. Tire 2
would be mounted on Rim 1 or 3 and replaced on the *left* side of the car.
And so on. In this manner, the "set" of the tires is maintained while
allowing equal wear on the tire from side to side.
Helen Annejackh@zehntel.UUCP (jack hagerty) (02/06/85)
> > Radial tires should be rotated front to back on the same side of the car, > according to my Saab dealer. As for my tires, I did not rotate them > at all (I know, I'm stupid). > > -- > /Don Don't be so hard on yourself. In the late '70s when FWD cars were starting to proliferate, a major tire manufacturer (Goodyear, I believe) did some long term tire wear studies. They found that if not rotated, the front tires of a FWD car will wear out in about 30k while the rears (which are "just along for the ride") will last at least three time longer, say 90k. If rotated, they found, the whole set lasts about 40k. Their reccomendation was to not rotate tires at all if you plan to keep your car a long time. The reasoning goes like this: If you rotate the tires, you'll be replacing them at 40k, 80k, etc., or 8 tires in the first 80k. If you don't rotate the tires you'll have to replace the fronts at 30k, 60k, 90k, etc., and the rears at 90k. This is a total of 8 tires in the first 90k, about 12% more mileage on the same number of tires. On our Fiat 128 I rotated the tires because I don't like the idea of different amounts of tread between the front and rear. As predicted, we got about 40k to a set. We've since replaced the Fiat with a Saab, and I've been rotating the tires for the same reason. On the other hand, I get about 60k to a set of tires on my Alfa which is RWD. I rotate them every 6k. -- Jack Hagerty, Zehntel Automation Systems ...!ihnp4!zehntel!jackh
prg@mgweed.UUCP (Phil Gunsul) (02/08/85)
<><><><>>>><><> What is your suggested 'rotation' going to do for your white-side-wall tires Helen??? BTW I would find it easier to turn the tire over instead of the rim ;-) Phil Gunsul -- AT&T Consumer Products
haapanen@watdcsu.UUCP (Tom Haapanen [DCS]) (02/13/85)
In article <15439@mgweed.UUCP> prg@mgweed.UUCP (Phil Gunsul) writes: >What is your suggested 'rotation' going to do for your white-side-wall >tires Helen??? BTW I would find it easier to turn the tire over instead >of the rim ;-) The suggested rotation has the added advantage of hiding those ugly white-wall tires. :-) \tom watmath!watdcsu!haapanen
hav@dual.UUCP (Helen Anne Vigneau) (02/15/85)
<*munch*>
Yeah, well, if yer so bloody worried about aesthetics, go ahead an' do it yer
own way. I'm sure it'll be just fine.
Helen Anne
{ucbvax,ihnp4,cbosgd,hplabs,decwrl,unisoft,fortune,sun,nsc}!dual!hav
If a man does not keep pace with his companions,
perhaps it is because he hears a different drummer.
Let him step to the music he hears,
however measured or far away.