"Low" spot of a rim?

[chrispx]

I'm trying to get a set of Dunlops to balance out
(3rd time) and came accros the following on the Dunlop site:

HARMONIC MARKINGS

Red dots on Dunlop high performance tires for match mounting purposes. These dots mark the 'high spot' of the tire, which is then matched with the 'low spot' on the rim to cancel out harmonic vibration.

Where is the "Low" spot on a 16x6 or 16x7 Fuch?

Thanks

Chris

[KTL]

To find the low spot on a wheel you should run a dial indicator on the inner and outer beads. But the general rule of thumb seems to be that the red dots are placed where the valve stem goes. Sometimes you'll find other manufacturers will put red dots and yellow dots on the rims. Then the question is which dot do you pick???!!!

Are you having problems with just one or all of the tires when balancing? Of course don't rule out a bent wheel........

[EarlyPorsche]

Low spot should be valve stem hole.

[dshepp806]

Originally Posted by EarlyPorsche

Low spot should be valve stem hole.

My understanding, as well. It would seem that one could place JUST the wheel on the balancer and verify this, no?

Best,

Doyle

[chrispx]

Thanks for the help.
I am getting a vibration at 75 mph that smooths out at 80. I'm pretty sure that it's not a bent rim as the vibration only started when I put on the new tires. I watched the tire guy balance these twice and saw them zero out both times (same machine, they were out both times though). The tires aren't mounted with the dots anywhere close to the stem and Dunlops "Harmonic Markings" statement made me think that I should try that route before giving the tires back to Tire Rack.

Chris

[dshepp806]

My last rears (done by myself and son-in-law at his LARGE Toyota shop) were aligned with the mark, then balanced on a force-balanced machine. My previous rears were purchased from and mounted by my P-wrench. He made note of something slightly damaged on one of the rear wheels (inner side,..but could be repaired,...chip?...I don't recall).... While we had the wheel off, we looked closely at what he may have been referring to and found nonething that caught our eyes.......we then mounted/balanced... I wish (NOW) I had spun that rim up on the machine and see the what the physics tell me (nice dots aside).. gnat's arse, I guess, should be on this balancing agenda..live and learn...will check this when I get the fronts mounted within a couple of weeks....will report back any "varations".

Why were the dots NOT used to begin with? I would certainly ensure this FIRST,..then,..see what results you get........

..or,.....did someone CHECK the rim to verify the dot's "data point" accracy,...find it a bit out,..then move from the dot to a different (better) balanced location? I have heard of someone going almost 180 degrees out on this !!!!! (Don't know if it's true or not.....)

A good Mounter will know.

Best,

Doyle

[hcoles]

+1 on a good mounter using a force balance machine will know
I went to a very good mounter the other day getting some tires changed on my BMW 540, I asked re dots... he said he has seen very often that the best location for the tire does not always line up with the dots... and has seen that the whole dot thing seems to be not as significant as it was in the past. One of my new mounted tires need what he thought was too much weight for a new tire and true rims. So he moved the tire around and got it to a point where it took a very small amount of weight. You can also watch while they spin the tire on the balancer... there should be almost no noticable runout. You can also put a dail indicator on your wheel to check it.. should be under 0.010" from high to low - IMO

[chrispx]

The installer used a force balance machine both times and things checked out. I was unaware of the red dot/yellow dot deal untill now and am going to give that a try today with a different shop.

Chris

[hcoles]

if you google and read you find out that there could be two different colors of dots on the tires. Each dot means something different and exactly what it means may vary somewhat across manufacturers. The common thing coming up is one color means "low or high" spot on the tire, the other color means "maximum or min. stiffness spot" in the tire.

e.g.

Apparently Falken's convention is a little different.

The yellow dot is the lightest spot and it is suggested to mount this above the valve stem.

The red dot is the high point, recommended to be mounted at the low point of the rim if so marked or, preferably, per actual measurement.

Per a product engineer at Falken Tire, these marks are just "starting" points for the tire installer to effectively mount your tires. With some of the new balancing equipment out there, the machine can do a more accurate job matching and balancing then simply relying on these dots alone.

[hcoles]

I didn't even read my own post very well.....

There are, I guess, three attribute:
- light and heavy spot on the tire
- low and high spot on the tire
- stiff and flexy spot on the tire

There may be dots on the tire to indicate some or all of these.

[RWebb]

Originally Posted by hcoles

if you google and read you find out that there could be two different colors of dots on the tires. Each dot means something different and exactly what it means may vary somewhat across manufacturers. The common thing coming up is one color means "low or high" spot on the tire, the other color means "maximum or min. stiffness spot" in the tire.

e.g.

Apparently Falken's convention is a little different.

The yellow dot is the lightest spot and it is suggested to mount this above the valve stem.

The red dot is the high point, recommended to be mounted at the low point of the rim if so marked or, preferably, per actual measurement.

Per a product engineer at Falken Tire, these marks are just "starting" points for the tire installer to effectively mount your tires. With some of the new balancing equipment out there, the machine can do a more accurate job matching and balancing then simply relying on these dots alone.

Bingo.

add yoko to search terms to find my old post on this or call a tecxh rep for dunlop

Roadmaster seems to be the best machine for all this

McPh. struts are fairly sensitive to this...

[dentist90]

Don't confuse roundness with balance. I have all four tires perfectly balanced, but at 70mph I get a vibration thru the front. Put it back on the balancer and spun it to check for roundness. Found the flat spot (I know how it happened too). At this point I have the option of shaving the tire or getting a new one. As a friend of mine once said... you can balance an egg, but you can't make it round.
You have to evaluate both. With the quality of tire manufacture now it is rare to have a detectable out of roundness at speeds under 120mph (unless you skid ). If you find you have to put 8oz of weight to balance, you should mark the rim and tire and reposition them. No weight will help a tire or rim that is out of round however.

[dshepp806]

out of round=all bets off....REPLACE!

Doyle

[chrispx]

Thanks to all.

The problem was solved after I went to an old-school place on the advise of the manager at another tire store. It turns out that all 4 tires were out of balance. The tech put them on his machine, 20 minutes later vibration gone.

Chris

[3.2 CAB]

With the talk about the "colored spots" on the tires, there are also "colored spots" on a lot of the Porsche wheel studs that I have seen. I have been told in the past when I asked about them, that the valve stem should be located as close to the colored stud end as possible. I had already known about the reason about the spots on the sidewall of the tire, but I never read anything about the one colored stud markings to find out just what that meant. I guess with all of the colored spots, it seems that they all need to line up(approx.) with the valve stems, both on the tires and on the hub lug studs. Just some additional info on the spots. Tony.

[hcoles]

again we give benefit of doubt to tire tech... again we are wrong
I'll bet 99% of tire techs don't get factory training.. more like 1 minute of do this and then do this.