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rws
01-25-2015, 02:06 PM
I got 4 Goodyear tires put on my truck, new of course. The shop had two people working on it from waht I could tell, one on each side. On the driver's side the tires were installed with the yellow dot lined with the valve stem. The other side, one is almost 180 degrees off, and the other was put on with the dot on the inside where you can't see it. This tire has a lot of weights installed. I can feel a slight vibration in the seat from about 50 to 55.

Some searches talk about aligning the dot with stem, but nothing definitive. Is there documentation to align these? I'm goibng to take it back, but would like some "ammo" to show them.

I bought this '02 new and have driven every mile on it, so I know what it feels and drives like.

A.K. Boomer
01-25-2015, 02:15 PM
I have no idea what to think anymore bout that, when running the motorcycle service dept. we always aligned the dot with the valve stem, but on cars iv seen such huge cut outs of custom wheels that the amount of material removed plus the hole has got to weigh more than a mostly rubber valve stem - yet on the cycles it was just a hole in steel sometimes - so you know the valve stem outweighed the simple hole

now enter in all the battery operated wheel pressure sensors that are integral to the valve stem and what they weigh,

point being is im sure it varies now,,,

other point being is now with most cars having wheel speed sensors why are they installing pressure sensors on them?

just use the variance of wheel speed to decide if a wheel is low or high on pressure...

janvanruth
01-25-2015, 02:45 PM
on the right side one of the tires is probably mounted in the wrong direction
see if there are direction indications on the tires

Mike279
01-25-2015, 04:49 PM
I would want to find out why the tire needs so much weight or maybe the tech bent your rim. I would ask them to remove the tire and show you the tire. Then check the rim. Insist on a new tire if that is the only one requiring excessive weight. Then make them balance the tires again until the vibration is gone. Tires can be defective in many ways, so don't let them blow you off. The only ammo you need is that you are not satisfied with the tire or tires in question. Mike

vpt
01-25-2015, 06:41 PM
We have had nothing but bad luck with goodyears on our trucks no matter where the dots are.

duckman
01-25-2015, 10:31 PM
I had 4 new tires put on my truck and went to a job 100 miles away, the vibration was horrible, went back and found the owner and told him fix it or put my old tires back on 1 tire had almost 7+ ounces on it to balance when he spun it on the balancer you could see the run out, he deflated the tire broke the bead and rotated the tire 180°, blew it back up and spun it on the balancer needed less than 1.5 ounces, then he went and found the tech that installed them the first and took him in to an office which I could have been a fly on the wall, but I was happy after that. So go back and make waves.

ironmonger
01-25-2015, 11:44 PM
<<snip>>

other point being is now with most cars having wheel speed sensors why are they installing pressure sensors on them?

just use the variance of wheel speed to decide if a wheel is low or high on pressure...

I don't believe the air pressure will affect the speed that a tire turns. The radius changes slightly due to the lost air, but the circumference of the tire is not changed by inflation. So it may change the torque but not the rpm. The belt is pretty much going to hold the tire circumference constant.

paul

kendall
01-26-2015, 12:45 AM
I don't believe the air pressure will affect the speed that a tire turns. The radius changes slightly due to the lost air, but the circumference of the tire is not changed by inflation. So it may change the torque but not the rpm. The belt is pretty much going to hold the tire circumference constant.

paul

With no weight on it, that would be correct, but with the weight of the car/truck on it the circumference would be reduced. weight on the tire will reduce the radius of the tire measured to the ground. A completely flat tire will have an effective radius approaching the rim size, more pressure increases the distance of the rim to ground and therefore the effective radius of the tire.

Arcane
01-26-2015, 12:48 AM
I don't believe the air pressure will affect the speed that a tire turns. The radius changes slightly due to the lost air, but the circumference of the tire is not changed by inflation. So it may change the torque but not the rpm. The belt is pretty much going to hold the tire circumference constant.

paul

Rolling radius changes with air pressure and rolling radius is what determines the number of revolutions of a tire in a given distance, not the circumference. This is proved by the fact that if I run equal air pressure in all four tires on my 4x4 I experience drivetrain bind when in 4 wheel drive (front end is heavier than the rear end and therefore squishes the front tires slightly more than the rears) but when I run 5 psi more in the front tires than the rears (50 vs 45) drivetrain bind goes away. I've experienced this on my previous 4x4 also.

PStechPaul
01-26-2015, 01:01 AM
Thinking about it, that does seem to make sense (that RPM vs road speed remain unchanged with changes in tire pressure). If you consider the worst case scenario of a flat tire where the rim is pinching the tire to the road, the entire circumference of the tire will still move the car the same distance per revolution, unless the bead separates. For a tire that is highly overinflated, there may be some stretching of the belts that give a greater diameter and circumference, but normally the entire surface of the tread will stay the same dimension until the tire is grossly underinflated. Even then, it just runs with a longer flat spot on the road and the top part of the tire will perhaps be at a greater distance from the center than the bottom portion. It might appear that the wheel rim acts like a sun gear with the tire as an internal tooth ring gear, but to get a difference in RPM there must be progressive motion of the surfaces of the two gears which cannot happen with a wheel and tire unless the bead slips.

However, another way of looking at this is that the true circumference of the tire changes with the geometry from a circle to a flatted circle, and the road distance on the flatted portion (a chord (http://en.wikipedia.org/wiki/Chord_%28geometry%29) of the circle) will be less than the full arc (http://en.wikipedia.org/wiki/Arc_%28geometry%29) of the circle between the same two points. I think this makes more sense and seems to be corroborated by Arcane's experience.

winchman
01-26-2015, 01:09 AM
Google is your friend.

"Since it is very hard to make a tire that is perfectly balanced, some tire manufacturers apply yellow dots that indicate the tire's light balance point and serve to help you balance the assembly while mounting the tire. The yellow dots should be aligned with the valve stem on both steel and aluminum wheels since this is the wheel's heavy balance point. This will help minimize the amount of weight needed to balance a tire and wheel assembly. So usually, whenever you see a yellow dot, match it up with the valve stem."

More here: http://www.tirebusiness.com/article/20070813/ISSUE/308139967/are-you-seeing-dots-those-color-coded-sidewall-markings-serve-a
https://www.google.com/search?q=yellow+dot+on+tires&ie=utf-8&oe=utf-8

vpt
01-26-2015, 08:19 AM
What is the red dot on tires for then?

http://i.imgur.com/1VqLoiN.jpg

A.K. Boomer
01-26-2015, 08:30 AM
Probably something to do with "maximus out of roundness"

A.K. Boomer
01-26-2015, 09:09 AM
Rolling radius changes with air pressure and rolling radius is what determines the number of revolutions of a tire in a given distance, not the circumference. This is proved by the fact that if I run equal air pressure in all four tires on my 4x4 I experience drivetrain bind when in 4 wheel drive (front end is heavier than the rear end and therefore squishes the front tires slightly more than the rears) but when I run 5 psi more in the front tires than the rears (50 vs 45) drivetrain bind goes away. I've experienced this on my previous 4x4 also.


Yup --- tires go through the ratio change right where they meet the road,,, with low tires there is a huge struggle going on,

that's why of course if you run too low you overheat them and destroy them, that's also why mileage gets drastically reduced - you are simply burning more fuel to heat not only the tires but leave a heated trail wherever you go...

To properly understand this ratio change all one needs to do is take a look at the big 4X4 with aggressive knobs,

you got these hillbillies putting tires like this on their trucks that spend 99% of the time on the road,

even at standard pressure this is a Fuque...

Tires are ALWAYS at there smallest radius at the bottom where they have to carry the weight of the vehicle - no matter the pressure, but nothing shows up the effects more than the big blocks of aggressive hides, they do two things - one they keep the tires from flexing as a unit, and two they create radical change in the engagement speeds of said blocks when entering onto the road, this is why these tires always get "radically chopped" and wear funny...

the bottom part of the tire dictates "true rotational speed" esp. if the tires a little low this means the block with the most weight on it wins,,, so it's not only smaller radius - it has control over all the rest of the tires larger circumference - well - now it does not take any abacus to figure out that we "have a problem"

you cannot effectively do this without great penalty - somewhere - somehow there is a nasty side effect of rubber binding,

on smooth tires the transition is gradual but wear is still drastically accelerated - but lets get back to the big blocks,

the blocks under the tire - the blocks with the most weight on them - the blocks with the longest established dwell - dominate,,, therefore - the blocks traveling at the higher speed due to them being at maximum radius are going faster than the speed of the road - and are entering into the road like this,
yet they have no major weight on them - so they instantly lose the tug of war battle the split second they engage --- what this results in is that the leading edge of these blocks will be reduced to match more closely the smaller radius of the tire on the road...

there is also a struggle as the block is leaving the road and wants to re-accelerate back to full circumference - but this is nowhere near the effect as rubber takes time to conform and also has mass,,, two of the things that really work against it in the leading edge blocks...

kendall
01-26-2015, 09:20 AM
For Falken tires, Yellow is lightest point of the tire, and should be mounted at the heaviest point of the rim, it's normally, but not always at the valve. Some rims will have a paint dot inside to mark the heavy spot. Red is the stiffest 'spring' section of the tire. Not all manufacturer's use the same colors, or use them to mark the same thing, some only mark the radial force variation (spring), others only mark the light spot. Need to check their site to see which dot means what.

CCWKen
01-26-2015, 10:21 AM
Why would they mark the stiffest "spring" section of the tire? And the sidewall is certainly not the stiffest part of a tire.

Red Dot tires used to be "Blemished" tires. Before that, they used to burn "BLEM" into the sidewall with a hot iron but stopped that when the new DOT rules came out. Blemished tires are suitable for highway use and meet all specifications but have some cosmetic deficiency. It could be anything from a miss-ground whitewall (or no whitewall on a whitewall part number) to bad lettering from the molding process.

ironmonger
01-26-2015, 10:45 AM
Graphics are fun...

https://www.youtube.com/watch?v=_2l5bOhHNxU

paul

A.K. Boomer
01-26-2015, 10:55 AM
LOL try it after many revolutions - one revolution and a tape measure is not going to cut it...

kendall
01-26-2015, 11:02 AM
Why would they mark the stiffest "spring" section of the tire? And the sidewall is certainly not the stiffest part of a tire.

Winchman's link covers it much better than I did, from his link:

Tires tend to have high spots and low spots. The difference between the high and the low is called radial runout. Radial runout changes the radius of the rotating assembly, causing it to raise and lower the vehicle as it rolls along. That gives the perception that the tire is ``hopping'' or ``bouncing'' down the road and ends up delivering a rough ride to the driver and irregular wear to the tread.

Radial force variation is similar to radial runout and is a result of a heavy or thicker area being manufactured into the tire due to variations in component thickness, placement and overlapping. Radial force variation applies more force against the road at the tire's thicker spot as the tire runs, which causes one sidewall to flex differently than the other. The result is tire/wheel assembly vibration and irregular tread wear.

To avoid or minimize these problems, whenever you see a red spot, match this up with the valve stem-unless you happen to have a steel wheel that has a dimple on the exterior side of the rim area. The dimple indicates the wheels' low spot and is spec'ed by some original equipment manufacturers so that they can match mount tires and wheels installed on new trucks at the factory.

If you see both a red as well as a yellow dot on the tire, the red dot takes priority. An easy way to remember this is the phrase ``Red Rules.'' Ignore the yellow dot and match the red dot to the wheel low point dimple as some vehicle manufacturers do or, if no dimple is marked on the wheel, align the red dot with the valve stem.

I should have followed his link before I posted.....

GKman
01-26-2015, 12:29 PM
I'm pretty sure that if a fully inflated wheel comes off a trailer that you are towing, it will pass you. Heard of it several times and think I saw it once. Angular velocity remains the same, at least briefly, the rolling radius increases so the speed increases.

A.K. Boomer
01-26-2015, 01:43 PM
I'm pretty sure that if a fully inflated wheel comes off a trailer that you are towing, it will pass you. Heard of it several times and think I saw it once. Angular velocity remains the same, at least briefly, the rolling radius increases so the speed increases.


You are correct - I did not even think of that but it's very simple and well documented...

apparently someone already beat me to my idea of using the speed sensors,,,

and yes it's all due to a lower tire rotating faster...

http://www.ehow.com/facts_7629879_do-pressure-monitoring-systems-work.html

ironmonger
01-26-2015, 01:47 PM
I'm pretty sure that if a fully inflated wheel comes off a trailer that you are towing, it will pass you. Heard of it several times and think I saw it once. Angular velocity remains the same, at least briefly, the rolling radius increases so the speed increases.

That tire is no longer bearing any weight, and the radius has increased, but what happens is that the tire no longer has to 'climb up' the distorted tread and the effective rolling resistance is much less... besides you probably hit the brakes when he funny noises and the new attitude of the tow vehicle sinks in.. :>)


Rolling radius changes with air pressure and rolling radius is what determines the number of revolutions of a tire in a given distance, not the circumference. This is proved by the fact that if I run equal air pressure in all four tires on my 4x4 I experience drivetrain bind when in 4 wheel drive (front end is heavier than the rear end and therefore squishes the front tires slightly more than the rears) but when I run 5 psi more in the front tires than the rears (50 vs 45) drivetrain bind goes away. I've experienced this on my previous 4x4 also.
I don't know what mechanism the 4WD scenario represents, but most modern 4WD's have the ability to engage or disengage the front to rear differential. With the differential locked out, who in their right mind is driving on any kind of pavement anyway. I was taught you went into the rough in 2WD so that you could get out if stuck by engaging the front's. Most 4WD has the front axle overdriven by a bit anyway, ie 4.10 rear versus 4.09 front.

Your next reading assignment:
http://www.stanceworks.com/forums/showthread.php?t=3216

note this bit:
NOTE: because the overall diameter of a steel belted radial is determined by the steel belts, there is little, if any, change to the overall diameter of the tire due to differences in rim width.

I'm just guessing, but I'll wager if you cut a tire apart, just one tire. and clamped the belt in between a couple of hooks, you could pick up the whole truck... If that belt won't stretch the circumference won't change. Think tank track, it doesn’t matter what size the drive sprocket is, when the track makes one full revolution you just traversed the circumference of the track.

paul

A.K. Boomer
01-26-2015, 01:57 PM
That tire is no longer bearing any weight, and the radius has increased, but what happens is that the tire no longer has to 'climb up' the distorted tread and the effective rolling resistance is much less... besides you probably hit the brakes when he funny noises and the new attitude of the tow vehicle sinks in.. :>)


I don't know what mechanism the 4WD scenario represents, but most modern 4WD's have the ability to engage or disengage the front to rear differential. With the differential locked out, who in their right mind is driving on any kind of pavement anyway. I was taught you went into the rough in 2WD so that you could get out if stuck by engaging the front's. Most 4WD has the front axle overdriven by a bit anyway, ie 4.10 rear versus 4.09 front.

Your next reading assignment:
http://www.stanceworks.com/forums/showthread.php?t=3216

note this bit:
NOTE: because the overall diameter of a steel belted radial is determined by the steel belts, there is little, if any, change to the overall diameter of the tire due to differences in rim width.

I'm just guessing, but I'll wager if you cut a tire apart, just one tire. and clamped the belt in between a couple of hooks, you could pick up the whole truck... If that belt won't stretch the circumference won't change. Think tank track, it doesn’t matter what size the drive sprocket is, when the track makes one full revolution you just traversed the circumference of the track.

paul

and again; http://www.ehow.com/facts_7629879_do...tems-work.html

Arcane
01-26-2015, 02:25 PM
I'm pretty sure that if a fully inflated wheel comes off a trailer that you are towing, it will pass you. Heard of it several times and think I saw it once. Angular velocity remains the same, at least briefly, the rolling radius increases so the speed increases.

In the very early 60's my B-I-L was coming back from Regina to our home town of Big Beaver listening to this song (https://www.youtube.com/watch?v=RghKdGn8h5A) when a wheel & tire passed his station wagon...his wheel & tire! :D Since then I've always associated this song with those events.

Arcane
01-26-2015, 02:56 PM
........I don't know what mechanism the 4WD scenario represents, but most modern 4WD's have the ability to engage or disengage the front to rear differential. With the differential locked out, who in their right mind is driving on any kind of pavement anyway. I was taught you went into the rough in 2WD so that you could get out if stuck by engaging the front's. Most 4WD has the front axle overdriven by a bit anyway, ie 4.10 rear versus 4.09 front. ..........

Only the people who have taken the time to eliminate drivetrain bind as I have...and even at that I slip in and out of 4x4 on a regular basis depending on the snow/ice cover but I like the ability to be able to drive short distances on pavement without having to always do so for fear of drivetrain bind.

Did you really believe I never took it out of four wheel drive???

I've owned and driven 4x4 trucks since the mid 70's and in all that time I have gone only a couple of years without one and presently I have both a 4x4 truck and an all wheel drive Suv.

rws
01-26-2015, 04:58 PM
Thanks for all the replies. I will take the truck back Saturday morning.

On this circumference thing. Most have seen a dragster with slicks take off. The tires are quite squashed sitting still, but once they hit the gas, it looks like the car raises a bunch. My point is, the tires are bought as a certain diameter. These guys mathmatically compute RPMs, gear ratios, tire diameters, to know how many RPMs they will be turning at the end of a 1/4 mile, assuming no slippage at the line. Maybe once they hit the gas the tire circumference remains the same?

PStechPaul
01-26-2015, 06:31 PM
One fine day, Kenny Rogers was driving his pickup truck on some perilous mountain roads, when he felt some vibration, and he saw the right front tire had come loose and was rolling along by itself down the road and over the edge and down the steep embankment. So he started singing:


https://www.youtube.com/watch?v=L0NDKtDSxKM

Some other related videos:
https://www.youtube.com/watch?v=7PEFJHnk1LM
https://www.youtube.com/watch?v=vdhxulLH5iI

Many more variations:
https://www.youtube.com/results?search_query=you+picked+a+fine+time+to+lea ve+me+loose+wheel