Dot on new tire - heaviest or lightest point?

[jje]

On some new tires Ive gone to put on a rim, there's a dot near the bead, does that indicate the heaviest or lightest part of the tire?

Should it go opposite or lined up with the valve? (Im not a pro, but I can use the machine)

 

[Quattro Pete]

It indicates the lightest part of the tire and should be lined up with the heaviest part of the rim which is usually the valve stem.

 

[GC4lunch]

Quote:

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On some new tires Ive gone to put on a rim, there's a dot near the bead, does that indicate the heaviest or lightest part of the tire?

Should it go opposite or lined up with the valve? (Im not a pro, but I can use the machine)

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Go to this URL: Scroll down to (or use your browser's text search to find) Coloured dots and stripes - whats that all about?.

 

[CapriRacer]

jje,

A couple of thoughts:

First, there is NOT universal agreement about the dots. They could be uniformity dots (a form of "out of round"), balance dots (which is what your question alludes to) or something else.

Second, the valve is usually the line up point for "out of round", not balance. The point of matching up the dots is to line up the high point (the most "out of round" point on the high end) of the tire, with the low point of the rim. The net result ought to be a "rounder" assembly. Please note that this valve isn't always the "low point" (it's somewhere else) and sometimes the rims aren't indexed at all.

But it does no harm in matching up the dots and sometimes is beneficial.

 

[CBODY67]

From what I recall from when "the dots" first appeared in the middle 1980s, it was about matching the low spot on the wheel (where the valve stem hole was punched) to the high spot of the tire (where the dot was placed). Matching "high" and "low" was supposed to, as mentioned, result in a tire/wheel assembly that "was rounder" for a smoooother ride. At that time, it was a "big deal" and every tire mounter knew about it, but that was "generations" ago, so not every tire mounter in more recent times could not know what it was all about.

Now that most larger tire stores have the sophisticated wheel balancers that will accurately (when correctly calibrated) measure "road force variation" (or "Ride Disturbance" as GY calls it) so that the tire/wheel relationship can be more accurately compensated for, basically making "the dots" obsolete when that type of balancer is used. Still, aligning "the dots" with that type of balancer can help make things better to start with, hopefully.

Enjoy!
CBODY67

 

[ewetho]

Yoko and Sumi had yellow and red dots. Start with yellow at the valve stem and if vibrations still occurs when tire is balanced then switch to red dot near valve stem. Only problem is on the new cars I get to see every day they have the wheels marked when new for weight and rarely is it at the valve stem. So those rules would mean nothing since the stickers are usually gone by the next set of tires.

 

[WalterMitty]

If you have access to the machine and time to kill, put the bare wheel with the valve stem on the balance machine and spin it up. Mark the heavy spots on the wheel and write down the values. There may be positions on the front and back of the wheel.

Mount the tire and spin up the assembly to see where it tells you to put the weight and how much it wants. Mark the spot on the tire and write down the weight.

Demount the tire and align the heavy spots opposite each other. If the tires are blackwall and bi-directional this includes picking a front and back on the tire/wheel combination. Inflate and spin up the assembly. Note the amount of weight it wants and the locations.

Once in a blue moon they'll cancel each other out, but if you end up with less weight on the assembly than you needed on your first combined pass, (and the position is opposite the "lightest" "heavy" spot) it's hard to improve on that.

I have played around and gotten the number lower, but it gets hard to make money with more effort. This is possible only when the new assembly indicates it needs weight in a third (new) heavy spot. Sometimes by moving the two heavy spots a small amount away from the new (third) spot the required weight will reduce again or go away.

In the early days of massive "mag" wheels and "Mickey Thompson 50's" this was the only way we could get some of the assemblies balanced with less than a pound of stick-on weights.

 

[mazduh30]

Steel rims have/had a dimple (low/heavy point ). Initial balance was yellow to valve stem. If a tire had both a red and yellow dot, "Red rules" when match mounting. Manufactor's now use a sticker (peels off) or now the valve stem position is more for style. Just simply figure the probability of wheels retaining their orginal runout after hundreds/thousands miles of use, the dot to valve stem just isn't used or isn't going to accurate. The sure fire thing is to find a balancer (Hunter) which is able to measure wheel runout and tire force variations under load.

 

[Axe Man]

For what it's worth my observations on the Sumitomo's that I had installed last week:

2 of the tires have a yellow and red dot approx 6 to 8 inches away from each other.

The 2 other tires have the dots almost on opposite sides of the tires.

None of the dots appear to be aligned with or installed opposite of the valve stem. It appears the installation was done without regard to dot placement.

I observed the installer installing weights and it appeared on at least 2 of the tires weights were put on both front and backside of the wheel.

The result: absolutely no shake or wooble. Steady at speeds exceeding 80 MPH on a 600 mile trip to Maryland this weekend. The balance is perfect and better than the factory tires.

 

[VelociRacer]

My question is how much total weight was used for each tire/wheel asy?

 

[WalterMitty]

Quote:

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None of the dots appear to be aligned with or installed opposite of the valve stem. It appears the installation was done without regard to dot placement.

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That's the way it's done the vast majority of the time these days and it works just fine. Only those of us with mild cases of OCD even consider match mounting tires for runout and imbalance.

http://www.tirerack.com/tires-techpage-1/17.shtml

It's just that old habits die hard. I remember when tires were so non-uniform that many of the top tire shops offered "tire truing" to give customers a smoother ride. If your tires were still bouncing and vibrating after *on-car* balancing, they had a big "tire lathe". They would put the tire/wheel assembly on it and would proceed to shave off the high spots until the tire was round and true. Then they'd rebalance on the car.

Of course, in those days we thought 15,000 miles was pretty good wear for set of tires. (yikes!)

 

[alreadygone]

Walt,

IT WAS!!!

Bob

 

[Papa Bear]

Atlas "buchrons".