the Dot (tire question) - K-Bikes.com - Excellence in Motion
 
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post #1 of 8 (permalink) Old Jun 25th, 2009, 6:14 am Thread Starter
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the Dot (tire question)

The painted dot on the sidewall is there to let you know where to put the tire in relation to the valve. Is it in line with the valve or 180 degrees from it? Is this convention the same for all brands? TIA
John Thompson
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post #2 of 8 (permalink) Old Jun 25th, 2009, 7:23 am
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All brands are in line with the valve stem as far as I know. Michelin does not use the "dot" identification system.

Bruce C
'04 K1200RS Capri Blue(totaled)
2008 Triumph Sprint ST

Last edited by brucecha; Jun 25th, 2009 at 9:36 am.
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post #3 of 8 (permalink) Old Jun 27th, 2009, 3:59 pm
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This should help



Match mounting involves positioning the tire onto the wheel to minimize or eliminate thefinal combination of radial force variation and/or imbalance (radial force variation is explained later in this article). One match mounting approach involves aligning the tire's point of maximum radial force variation (its high spot) to the wheel's radial low spot (where the wheel's radial runout is the lowest). This is called the Uniformity Method. The other approach involves simply aligning the tire's lightest balance point to the wheel's heaviest balance point, called the Weight Method.

OE tire suppliers are required to mark a tire's radial runout high point, and OE wheel makers are required to mark a wheel's radial runout low point. This makes it easy for the OEMs to match-mount tires to wheels from a radial force variation standpoint during production. In some cases, these marks are made with paint dots that help service technicians remount tires down the road. However, sometimes these marks are made using temporary stickers, which either fall off or are removed after mounting. This leaves no readily visible reference marks for the tire technician for future service.

If a tire does feature color dots on the sidewall, one or two dots may be used. A red dot indicates the tire's radial runout high point. A yellow dot indicates the tire's point of least weight, from a balance standpoint.

For decades, it was common practice in the aftermarket to mount a tire so its red dot aligned with the wheel's valve stem, since the valve stem area was normally assumed to be the wheel's lowest point of radial runout. Aligning the tires high point to the wheel's low point (theoretically) reduces or eliminates the chance of developing a radial force variation (RFV) in the tire/wheel assembly.' RFV (again, an issue of runout, not imbalance) can cause a vibration that might be mistakenly diagnosed as an imbalance problem.

Times change. With the advent of styled custom wheels, the valve stem location may no longer indicate the wheel's low radial runout spot. In other words, it may no longer be viable to assume that aligning a tire's.red dot to the wheel's valve stem will address any potential RFV issues.

Consequently, a procedure that was once easy has now become complicated. The only way to accurately matchmount a tire to a wheel is to actually measure tire and wheel runout. The end goal remains the same: to align the tire's high point to the wheel's low point. The wheel itself can be easily checked for radial runout by mounting it to a hub and slowly rotating it while monitoring the rim edge with a rigidly mounted dial gauge. However, the only acceptable method to check the assembled tire/wheel package for radial uniformity under load is to use a state-of-the-art wheel balancing machine that features a load-roller that applies road-simulated load to the inflated tire. Such a machine will not only check for dynamic balance but will also locate the tire's high spot. If this high spot doesn't correlate to the wheel's low spot, the machine will let you know where to relocate the tire on the wheel to minirnize RFV

If you don't have access to a roadwheel type of balancing machine, and you don't know where a wheel's lowest radial runout spot is located, you can default to using the Weight Method, which involves aligning the tire's yellow dot to the wheel's valve stem.

As you can see, tire/wheel match mounting isn't a cut-and-dried method. Your approach to match mounting will depend on several variables:

* whether the tire is runout- and weight-matched,

* whether the wheels low runout spot can be determined, and

* whether you have access to a loadapplying balancing machine.

Regardless of the specific approach you take, it's important to understand that "stacked-up" runout and imbalance conditions can be addressed. Of course, once tire matching has been accomplished, the mounted package must then be checked and corrected for dynamic balance.

There are two types of radial runout -static and dynamic. Static runout, as we noted earlier, refers to the high spot of the tire, a physical characteristic that can be measured with no load placed on the tire. Radial force variation, however, refers to a dynamic runout condition, which occurs only when the tire runs at speed, under load, due to variations in construction stiffness.


Some times "not knowing" is better!
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post #4 of 8 (permalink) Old Jun 27th, 2009, 5:11 pm
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Quote:
Originally Posted by brucecha
Michelin does not use the "dot" identification system.
Do you know why? Do they use something else instead?
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post #5 of 8 (permalink) Old Jun 28th, 2009, 5:11 am
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Just a rumor...But have heard that they use the bar code that is on the tire bead as the indicator.....and I have been told that mich. tires are molded so close to perfect that they don't need an indicator.....so where lies the truth?...I would call mich. them selves and ask...
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post #6 of 8 (permalink) Old Jun 28th, 2009, 8:15 am
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"But have heard that they use the bar code"

That makes sense to me. On each side of the bar code on my tires (new in the box) there is yellow paint spots. I understood the red dot system, but could never find them when I switched to Michelin's.

Thanks!

Paul

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post #7 of 8 (permalink) Old Jun 29th, 2009, 6:12 pm
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El Barto,
How much does clipping a car throw off your tire balance?

Ray
04 GT
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post #8 of 8 (permalink) Old Jun 29th, 2009, 6:30 pm
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It didn't knock any weights off and as far as I can tell the tires didn't rotate on the wheel when the anti-locks were screaming at me .

The conclusion I can draw is the tires remain balanced and I remain unbalanced.

El Barto
Ride fast.......Get there before the accident!
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