Buying & mounting new tires tomorrow (two questions)

On Wed, 31 Aug 2011 12:59:44 +0000 (UTC), Tegger wrote:
> If you have to tell them how to mount tires, you shouldn't be going to
> them.
>
> <http://www.nsxprime.com/FAQ/TireWheel/Balancing.htm>

Every few years, I get tires mounted.

Every time, I ask them to mount them properly.

Almost NEVER do they even KNOW about the red/yellow dots.

I know about them ... but I always forget which one is the heavy spot and
which is the light spot ... and which goes across from the valve and which
goes next to the valve (on aluminum wheels).

These are Big-O, America's Tires, Goodyear type places. So, I think NONE of
them know how to properly mount tires.

On Wed, 31 Aug 2011 08:01:51 -0700, jim beam wrote:

> no amount of "dot
> alignment" will help you. garbage tires are garbage tires. period.

Doesn't it enable less weight to be used?

On Wed, 31 Aug 2011 08:40:53 -0500, Vic Smith wrote:

> forget about the dots. Meaningless when force balanced.

Doesn't it allow less weight to be used?

On Wed, 31 Aug 2011 07:35:27 -0700, jim beam wrote:
> very misleading tire rack rating.

I bought the tires 'by the numbers'.

Tire Rack had about 40 tires that fit.

So I whittled down the list to one tire by assessing:
* Size = same as original
* Traction = AA only (wet)
* Temperature = A only
* Treadwear = the bigger the better
* Speed = the higher the better
* Load range = the higher the better
* cost (including tax & shipping & mounting & balancing & disposal)

I 'wish' there was a way to assess dry traction and road noise ... but as
far as I know, there are no tests that you can find for 40 tires to
compare.

The tire rack reviews seem to all be written by high school dropouts, by
the way - so, for the final three tires, I did read the reviews, but it was
a waste of time. They were all good to some degree or another.

On 08/31/2011 12:40 PM, SF Man wrote:
> On Wed, 31 Aug 2011 08:01:51 -0700, jim beam wrote:
>
>> no amount of "dot
>> alignment" will help you. garbage tires are garbage tires. period.
>
> Doesn't it enable less weight to be used?

sure. and you can "balance" a square wheel too. but if the wheel is
not round, or the tire is not round, or even has different tensions in
the cordage, the wheel will never "feel" balanced on the road, no matter
what you do.


--
nomina rutrum rutrum

On 08/31/2011 12:39 PM, SF Man wrote:
> On Wed, 31 Aug 2011 12:59:44 +0000 (UTC), Tegger wrote:
>> If you have to tell them how to mount tires, you shouldn't be going to
>> them.
>>
>> <http://www.nsxprime.com/FAQ/TireWheel/Balancing.htm>
>
> Every few years, I get tires mounted.
>
> Every time, I ask them to mount them properly.
>
> Almost NEVER do they even KNOW about the red/yellow dots.
>
> I know about them ... but I always forget which one is the heavy spot and
> which is the light spot ... and which goes across from the valve and which
> goes next to the valve (on aluminum wheels).
>
> These are Big-O, America's Tires, Goodyear type places. So, I think NONE of
> them know how to properly mount tires.

even if you pay attention to the dots on the tires, it's pointless
trying to align them with valves or dots on the wheel unless the wheel
is brand new. once it's been on the road, and run a few potholes, a few
curbs and generally "lived a little", its balance will have shifted.
thus, given that most of the big shops use good quality balance machines
that take this into account, you're more likely to be witnessing the
tire being aligned to the wheel's /real/ heavy spot than anything else.
and if you're getting a negative reaction to your questioning, what
would the reaction be from your dentist if you started questioning their
practices? do you know more then them? tire shops don't ignore stuff
just so you can come back, bitch, and cost them money in warranty work.

the bottom line is whether the wheel drives balanced or not. if it
doesn't, maybe the shop didn't do it right, but maybe you have a square
tire. if it drives well, wtf are you worried about?


--
nomina rutrum rutrum

On Wed, 31 Aug 2011 12:59:13 -0700, jim beam wrote:

> sure. and you can "balance" a square wheel too. but if the wheel is
> not round, or the tire is not round, or even has different tensions in
> the cordage, the wheel will never "feel" balanced on the road, no matter
> what you do.

I guess I'm confused. These tires I bought cost $185 each.

I don't 'think' they're 'garbage' tires, as you seem to be suggesting
(unless I misunderstand your kind reply). All I'm asking is where the
red/yellow dot goes when mounting, because the tire mounting guys often
don't care (I've seen this happen every time I get tires mounted). They
assume you don't know that the red dot even exists!

Here's the answer, thanks to a previous poster in this thread:
http://www.bridgestonetrucktires.com...0ask%20doc.pdf

"The red dot indicates the ´radial force variation first harmonic maximum.¡
Thatÿs a mouthful, of course, but itÿs a way of indicating where the
centrifugal force tending to pull the rotating tire away from the wheel is
greatest.

Another way of looking at it is that in a sense, if the tire were out of
round, the red dot would more or less correspond to the ´high point¡ or
place where radial runout forces are greatest.

Why not just measure the runout of the tire?

The radial force variation measurement is much more accurate in predicting
tire behavior. In fact, the red dot often isnÿt located exactly at the
´high point.¡ Instead, it accurately marks where the runout-like force is
greatest.

But, if you think of it as marking the tireÿs ´effective¡ high point, it
becomes pretty obvious why youÿd match the red dot with the steel wheel
´low point¡ dimple. Itÿs as though the tire is a bit ´thicker¡ (from wheel
to tread) in the red dot area.

And, since the dimple marks the low point on the steel wheel, you might say
the wheel is a bit ´thinner¡ (from axle to flange edge) where the dimple
is.

And on aluminum wheels?

At the red dot location, the tire is trying to pull away from the center of
the axle a little bit, as a result of higher centrifugal force.

As in our last example, itÿs as though the tire is a bit ´thicker¡ near the
red dot, which has the effect of pushing the wheel and axle upward as the
red dot gets to 6 oÿclock.

Meanwhile, the fact that the wheel is a bit heavier at the valve stem
location generates a centrifugal force effect trying to pull the axle
downward as the valve stem gets to 6 oÿclock.

Those forces tend to counteract each other.

And the final result?

Matching the dots is no substitute for balancing tire and wheel assemblies.
What it does, however, is give you the best start, so you are more likely
to use less total weight to bring an assembly into balance.

Since the red dot indicates where the tire behaves as though it has a high
spot, at the 6-oÿclock position, the road is pushing the tire upward, while
centrifugal force from the wheel heavy spot is trying to push the wheel
downward. These forces tend to counteract each other.

The only asymmetrical hole bored into aluminum wheels is the hole where the
valve stem will be mounted.

A typical valve stem weighs about 1.2 ounces more than the aluminum that is
bored out of the wheel where it is mounted.

The red dot marks the maximum point of radial force variation, and behaves
as though it were a ´high point¡ on the tire."

On 08/31/2011 01:09 PM, SF Man wrote:
> On Wed, 31 Aug 2011 12:59:13 -0700, jim beam wrote:
>
>> sure. and you can "balance" a square wheel too. but if the wheel is
>> not round, or the tire is not round, or even has different tensions in
>> the cordage, the wheel will never "feel" balanced on the road, no matter
>> what you do.
>
> I guess I'm confused. These tires I bought cost $185 each.
>
> I don't 'think' they're 'garbage' tires, as you seem to be suggesting
> (unless I misunderstand your kind reply). All I'm asking is where the
> red/yellow dot goes when mounting, because the tire mounting guys often
> don't care (I've seen this happen every time I get tires mounted).

i guess i have to say it again - they're probably mounting in accordance
with the /real/ dynamic weighting of the wheel that has been /driven/,
not per the "guess it's balanced" approach you can use with a new wheel.


> They
> assume you don't know that the red dot even exists!
>
> Here's the answer, thanks to a previous poster in this thread:
> http://www.bridgestonetrucktires.com...0ask%20doc.pdf
>
> "The red dot indicates the �radial force variation first harmonic maximum.�
> That�s a mouthful, of course, but it�s a way of indicating where the
> centrifugal force tending to pull the rotating tire away from the wheel is
> greatest.
>
> Another way of looking at it is that in a sense, if the tire were out of
> round, the red dot would more or less correspond to the �high point� or
> place where radial runout forces are greatest.
>
> Why not just measure the runout of the tire?

why not indeed. but now you've measured it, what are you going to do?
bend the wheel so the tire's round? at what speed?


>
> The radial force variation measurement is much more accurate in predicting
> tire behavior. In fact, the red dot often isn�t located exactly at the
> �high point.� Instead, it accurately marks where the runout-like force is
> greatest.

at what speed? harmonics can move that thing around. ask anyone who
has balanced helicopter rotors.


>
> But, if you think of it as marking the tire�s �effective� high point, it
> becomes pretty obvious why you�d match the red dot with the steel wheel
> �low point� dimple. It�s as though the tire is a bit �thicker� (from wheel
> to tread) in the red dot area.
>
> And, since the dimple marks the low point on the steel wheel, you might say
> the wheel is a bit �thinner� (from axle to flange edge) where the dimple
> is.
>
> And on aluminum wheels?
>
> At the red dot location, the tire is trying to pull away from the center of
> the axle a little bit, as a result of higher centrifugal force.
>
> As in our last example, it�s as though the tire is a bit �thicker� near the
> red dot, which has the effect of pushing the wheel and axle upward as the
> red dot gets to 6 o�clock.
>
> Meanwhile, the fact that the wheel is a bit heavier at the valve stem
> location generates a centrifugal force effect trying to pull the axle
> downward as the valve stem gets to 6 o�clock.
>
> Those forces tend to counteract each other.
>
> And the final result?
>
> Matching the dots is no substitute for balancing tire and wheel assemblies.
> What it does, however, is give you the best start, so you are more likely
> to use less total weight to bring an assembly into balance.
>
> Since the red dot indicates where the tire behaves as though it has a high
> spot, at the 6-o�clock position, the road is pushing the tire upward, while
> centrifugal force from the wheel heavy spot is trying to push the wheel
> downward. These forces tend to counteract each other.
>
> The only asymmetrical hole bored into aluminum wheels is the hole where the
> valve stem will be mounted.
>
> A typical valve stem weighs about 1.2 ounces more than the aluminum that is
> bored out of the wheel where it is mounted.
>
> The red dot marks the maximum point of radial force variation, and behaves
> as though it were a �high point� on the tire."

you're giving much too much credence to dumbed down pseudo-tech sales
crap you read on the net. take the tires to a shop with a decent
balance machine like a hunter, and stop second-guessing people like its
designers who are good at math and have analyzed the problems in
exhaustive detail.


--
nomina rutrum rutrum

On Wed, 31 Aug 2011 13:08:01 -0700, jim beam wrote:
> even if you pay attention to the dots on the tires, it's pointless
> trying to align them with valves or dots on the wheel unless the wheel
> is brand new.

Good point.

> do you know more then them? tire shops don't ignore stuff
> just so you can come back, bitch, and cost them money in warranty work.

I don't know more than they; but I still want my tires mounted properly.

The manufacturer doesn't go to the trouble of putting the dots on the tire
for no reason at all (do they?).

Unfortunately, after reading the PDF that someone referenced in this
thread, I now realize the yellow and red dots are vastly more than just a
'heavy' spot or a 'light' spot.

For example, witness these quotes:
"The red dot indicates the ´radial force variation first harmonic maximum"
with the result that "At the red dot location, the tire is trying to pull
away from the center of the axle a little bit, as a result of higher
centrifugal force".

So, I printed it out and will bring it to the tire shop because the last
time I had tires mounted, they told me they never heard of the red dot
(that was at Goodyear, btw).

I showed it to them on all their tires, and they said they've never noticed
it before. So, I just wanted to check, ahead of time, where the red dot
goes.

Thanks to that PDF, I have the answer. It's the right way to balance a tire
& wheel assembly.

On Wed, 31 Aug 2011 12:41:00 -0700, SF Man >
wrote:

>On Wed, 31 Aug 2011 08:40:53 -0500, Vic Smith wrote:
>
>> forget about the dots. Meaningless when force balanced.
>
>Doesn't it allow less weight to be used?

Force balance does that. My kid did this for a couple years at Just
Tires. The machine determines where to rotate the tire on the rim.
He said the dots seldom match what the machine says.
Seldom enough to be random.

--Vic