Tires are out-of-round

[Ken Gilbert]

I went on vacation for a couple of months, and left my Outback sitting
inside my garage during that time. Got back and there is a severe vibration
in the steering above 90kph (55mph). Took it to the dealership to have them
rebalance the tires, and they came back and said that it can't be
rebalanced, everytime they add weight to it in the balancing machine it asks
for more weight to be added. They suggested that the tires are "out of
round". Now these are expensive tires (Nokians) and I'd rather not have to
completely replace them. I was wondering if there was an accepted way of
getting tires back into round. I was thinking that maybe I would overinflate
them to say about 45psi or something and leave them that way for a couple of
weeks of normal usage. Would this work?

Yousuf Khan

whenever this has happened to me, i've ignored it and it went away on its own.

the tire with sealant in it may not be able to be rescued though.

jm2c
ken

 

[Yousuf Khan]

the tire with sealant in it may not be able to be rescued though.

Why?

Yousuf Khan

 

[Rick Courtright]

Why?

Hi,

It's ~possible~ the sealant has coagulated into a mass at one location
in the tire. If you weren't having problems with the rest of the tires,
too, I'd suggest squirting a small amount of water into the tire with
the valve stem removed, then reinflating and driving. Many, if not most,
sealants are water-based and if they haven't dried completely may
reconstitute themselves slightly and spread around removing the "lump."

Rick

 

[Yousuf Khan]

Hi,

It's ~possible~ the sealant has coagulated into a mass at one location
in the tire. If you weren't having problems with the rest of the tires,
too, I'd suggest squirting a small amount of water into the tire with
the valve stem removed, then reinflating and driving. Many, if not most,
sealants are water-based and if they haven't dried completely may
reconstitute themselves slightly and spread around removing the "lump."

No, it's not likely to have coagulated, the sealant was just put on recently
*after* the flatspotting took place. I figured that there might have been a
leak in the tire because it had gone low, so I put the sealant in. So it's a
recent application. Little did I realize that it would throw off the
balancing scales as much as it did.

Anyways, I've pumped the air upto 40psi in the front and 36psi in the rear
(heavier front end when not loaded in the back), up from 34 and 32
respectively. It seems to have made the vibration move up in speed range and
lessened the severity; it's now happening after 90km/h rather than 80 km/h.
I think if I pump it up another 2psi front and rear, it'll go away at my
usual highway driving speeds.

Yousuf Khan

 

[John O]

I think if I pump it up another 2psi front and rear, it'll go away at my

usual highway driving speeds.

At 42 psi, you might be creating other problems, not the least of which
involves really bad emergency handling. I wouldn't run the tires at that
pressure, especially at highway speeds. But that's just me.

-John O

 

[Yousuf Khan]

At 42 psi, you might be creating other problems, not the least of which
involves really bad emergency handling. I wouldn't run the tires at that
pressure, especially at highway speeds. But that's just me.

Well, the snow is all gone now, so I don't think number of emergencies is
going to be all that great in number right now. Besides this is just
temporary until the vibration goes away. Once I start noticing no
vibrations, I'll start bleeding the tire pressures down again.

Yousuf Khan

 

[Paul Pluzhnikov]

Well, the snow is all gone now, so I don't think number of emergencies is
going to be all that great in number right now.

You don't need "great number" of emergencies.
Just one is enough to kill you (or someone else).

Cheers,

 

[John O]

Well, the snow is all gone now, so I don't think number of emergencies is

going to be all that great in number right now. Besides this is just
temporary until the vibration goes away. Once I start noticing no
vibrations, I'll start bleeding the tire pressures down again.

If your Subie was able to hold the ground at 30 psi when you hit 1g on dry
concrete, at 42 psi it might just break loose at .5g. Your stopping distance
during a hard braking situation will be much longer. On wet pavement, you
could end up with handling similar to a frozen road. If you hit a big
pothole it could blow the tire. The strain on your suspension will be much
greater with overinflated tires.

That's the way I see it, but it's your car.

-John O

 

[Yousuf Khan]

If your Subie was able to hold the ground at 30 psi when you hit 1g
on dry concrete, at 42 psi it might just break loose at .5g. Your
stopping distance during a hard braking situation will be much
longer. On wet pavement, you could end up with handling similar to a
frozen road. If you hit a big pothole it could blow the tire. The
strain on your suspension will be much greater with overinflated
tires.

That's the way I see it, but it's your car.

Okay, okay, everybody, I won't raise the pressure up any further than where
I've already taken it to.

Yousuf Khan

 

[D L YOUNG]

To Yousuf Khan-

I had a similar vibration as you described which turned out to be due to non
uniform wear which was in turn due to misalignment. The OEM tires could not
be saved and were replaced- after only about 13000 miles.

I will have to deal with similar vibration of my Nokian snow tires next
fall- but first I'll check how my new all-season tires behave in snow.

I suspect the car (02 Forester S) was was supplied originally with the
suspension misaligned but who is to know for sure? There was no obvious
problem on the road, but the car does handle better after realigning and
fitting new tires.

Hope this helps.. Doug.

 

[Ken Gilbert]

If your Subie was able to hold the ground at 30 psi when you hit 1g on dry
concrete, at 42 psi it might just break loose at .5g. Your stopping distance
during a hard braking situation will be much longer. On wet pavement, you
could end up with handling similar to a frozen road. If you hit a big
pothole it could blow the tire. The strain on your suspension will be much
greater with overinflated tires.

That's the way I see it, but it's your car.

-John O

whoh... what's all this about his tire pressures being "too high?"

stay under the tire mfg's rated sidewall max pressure and you will be
FINE.

in fact, i'll bet a new set of falken azenis that his tires with
doorsill sticker +10 psi pressure will outperform yours at doorsill
sticker pressures.

will his car eventually develop more squeaks and rattles from a
harder/harsher ride? pretty likely. will he lose 50% of his
traction... ABSOLUTELY NOT!!! to even suggest that it is true speaks
volumes about your experience with adjusting tire pressures.

imo, people should stick to things they KNOW about.

ken

 

[Cam Penner]

whoh... what's all this about his tire pressures being "too high?"

stay under the tire mfg's rated sidewall max pressure and you will be
FINE.

in fact, i'll bet a new set of falken azenis that his tires with
doorsill sticker +10 psi pressure will outperform yours at doorsill
sticker pressures.

will his car eventually develop more squeaks and rattles from a
harder/harsher ride? pretty likely. will he lose 50% of his
traction... ABSOLUTELY NOT!!! to even suggest that it is true speaks
volumes about your experience with adjusting tire pressures.

IME, too high a tire pressure (above recommended pressures)
gives:
1) rougher ride
2) better mileage
3) more "chatter" over bumps - ABS kicks in more often
4) more understeer
5) less traction

Yeah, increase the pressure if you're increasing the weight
of the vehicle - that keeps the footprint the same. But a
25% change in PSI? That's going to give you nearly 25%
less tire in contact with the road. That's going to impact
your braking distances significantly.

imo, people should stick to things they KNOW about.

Ain't this the truth.

 

[Paul Pluzhnikov]

will he lose 50% of his traction... ABSOLUTELY NOT!!!
imo, people should stick to things they KNOW about.

May I ask you
- what do you *know* about traction of overinflated tires?
- whether you've ever ridden a "road" bicycle with tires at
100+PSI, and had to do an emergency stop?

Cheers,

 

[Edward Hayes]

Since radials have steel belts to hold the tread flat I doubt that much
footprint is lost due to increasing the pressure (within limits of course).
People who autocross their vehicles often run 10 psig over the door sticker
for added traction and control. Ed

 

[John O]

will his car eventually develop more squeaks and rattles from a

harder/harsher ride? pretty likely. will he lose 50% of his
traction... ABSOLUTELY NOT!!! to even suggest that it is true speaks
volumes about your experience with adjusting tire pressures.

imo, people should stick to things they KNOW about.

Notice I used the word MIGHT.

The poor guy has rotten tires, and his gut tells him to blow them suckers up
to solve the problem. he's asking for a spinout or worse...maybe he spins
into you or me...but you 'holler' at me??? Whatever.

-John O

 

[Ken Gilbert]

why don't any of you folks who think the doorsill pressure is gospel
go to a local autocross, and ask those who are ACTUALLY COMPETING what
tire pressures they run. after you gather that information, ask those
folks who go to road racing tracks what tire pressures THEY run.
hint: it's around 40psi.

the doorsill pressure is a SUGGESTION to those who cannot determine
for themselves what a properly inflated tire wears like. for 99% of
the time the doorsill pressure can be taken as a minimum, the sidewall
pressure the maximum, and the optimal somewhere between the two. if
you drive like granny and you like a cushy soft "american" ride, then
sure, use the doorsill. if you find yourself cornering like a madman
and the shoulders of your tires wearing the worse for it, up the
pressure. your max lateral acceleration will increase as a result;
it's that simple.

as for this thread, i'm done arguing with armchair engineers.

ken gilbert

 

[Yousuf Khan]

The poor guy has rotten tires, and his gut tells him to blow them
suckers up to solve the problem. he's asking for a spinout or
worse...maybe he spins into you or me...but you 'holler' at me???
Whatever.

The theory remains just that a theory, the reality has now been tested. We
got some nice slick conditions here over the weekend, not snow, but cold
rain and hail, and the high pressure tires performed exactly as well as they
did at lower pressures. Could not tell a difference. Didn't take them any
easier than I normally do under these circumstances either.

Yousuf Khan

 

[John O]

The theory remains just that a theory, the reality has now been tested.

Thanks for taking that bullet.

-John O

 

[Yousuf Khan]

Thanks for taking that bullet.

Actually remembering back to the debates about the Ford Explorer/Firestone
Wilderness tire blowout controversy, several years ago, I think the problems
occurred because the recommended tire pressures on the door sticker was too
low, and Firestone claimed that it wouldn't have happened if Ford had
recommended a higher tire pressure. That's my recollection anyways.

Yousuf Khan

 

[Cam Penner]

@news04.bloor.is.net.cable.rogers.com>, news.20.bbbl67
@spamgourmet.com says...

Actually remembering back to the debates about the Ford Explorer/Firestone
Wilderness tire blowout controversy, several years ago, I think the problems
occurred because the recommended tire pressures on the door sticker was too
low, and Firestone claimed that it wouldn't have happened if Ford had
recommended a higher tire pressure. That's my recollection anyways.

Which underscores the importance of proper tire pressure.
Premature catastrophic tire failure can happen upon either
under or over inflation. It is a dangerous logical fallacy
to assume that just because the Ford Explorer's door
sticker was wrong that all door stickers are wrong. If you
are in doubt as to what may happen - contact two people.
One of them being the manufacturer of the car, and the
other being the manufacturer of the tire. They are the
ones best equipped to know. Almost everyone else is
speculating.