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  • OT- Another Tire ?

    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.

  • #2
    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...

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    • #3
      on the right side one of the tires is probably mounted in the wrong direction
      see if there are direction indications on the tires

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      • #4
        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

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        • #5
          We have had nothing but bad luck with goodyears on our trucks no matter where the dots are.
          Andy

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          • #6
            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.

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            • #7
              Originally posted by A.K. Boomer View Post
              <<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
              paul
              ARS W9PCS

              Esto Vigilans

              Remember, just because you can doesn't mean you should...
              but you may have to

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              • #8
                Originally posted by ironmonger View Post
                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.

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                • #9
                  Originally posted by ironmonger View Post
                  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.
                  Location: Saskatoon, Saskatchewan, Canada

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                  • #10
                    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 of the circle) will be less than the full arc of the circle between the same two points. I think this makes more sense and seems to be corroborated by Arcane's experience.
                    Last edited by PStechPaul; 01-26-2015, 01:14 AM. Reason: alternate explanation
                    http://pauleschoen.com/pix/PM08_P76_P54.png
                    Paul , P S Technology, Inc. and MrTibbs
                    USA Maryland 21030

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                    • #11
                      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/...rkings-serve-a
                      https://www.google.com/search?q=yell...utf-8&oe=utf-8
                      Any products mentioned in my posts have been endorsed by their manufacturer.

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                      • #12
                        What is the red dot on tires for then?

                        Last edited by vpt; 01-26-2015, 08:22 AM.
                        Andy

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                        • #13
                          Probably something to do with "maximus out of roundness"

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                          • #14
                            Originally posted by Arcane View Post
                            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...
                            Last edited by A.K. Boomer; 01-26-2015, 09:22 AM.

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                            • #15
                              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.

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