I mount and balance my own tires. I have always matched up the tires balancing spot with the valve stem until I started balancing the wheel alone.  I have found in no case is the valve stem the heavy spot. The only references I have found about the painted spot on some tires is that this is the light spot which means that the valve stem is assumed to be the heavy spot.

Since none of my wheels heavy spot matches the valve stem and the wheel I am balancing at the moment  (2002 Nina500R)is off by more than 90 degrees I started wondering. Why is the valve stem assumed to be the heavy spot?  Does the weight of the rubber and tiny amount of brass (of typical stem, not of TPMS) overcome absence of steel or aluminum material removed when drilling the hole?

I think something is off in this conventional wisdom  of valve stems being the heavy spot and would like to hear opinions from the wise and you wise guys as well.

I've not dealt with many wheels, 3 sets from three different bikes.   Plus, I check them on my home balancer. It beat Harbor freight quality, but barely.  Based on that, one rim from the six total has the heavy spot at the valve stem.   The other 5 are at random locations on each.

I do think its close enough to not matter much.  Its a fun diy job since  a person can get so fanatical about balance, but by the time I start trimming a 10 g weight with a dremel tool.....its just for me.

I've not dealt with many wheels, 3 sets from three different bikes.   Plus, I check them on my home balancer. It beat Harbor freight quality, but barely.  Based on that, one rim from the six total has the heavy spot at the valve stem.   The other 5 are at random locations on each.

I do think its close enough to not matter much.  Its a fun diy job since  a person can get so fanatical about balance, but by the time I start trimming a 10 g weight with a dremel tool.....its just for me.

Yeah, the dremel trimming is a little overboard. I trim my weights with a hammer and chisel, much quicker.

I have balanced lots of tires. Some for road use, some for track and even did
a few sets for a Bonneville bike. Did not set any records but did manage to brake
200. I have found I need to go to the tire manufactures web site and find out
exactly what they are trying to tell me with all those dots. I've seem red, green
and yellow dots, oh wait that was when I poke my eye. Anyway read what the
manufacture has to say and you may find something new.

I just changed my rear tire yesterday and yes I just assumed the valve stem was the heavy spot. I think it is a pretty good assumption on the C14 due to the TPMS. But I like your thinking and the next time I have a tire off I'm going to balance the rim and mark it. 

10 gram weight is the smallest weight I use and have road tested my balancing to 130 with zero vibration. So dremel or chisel a smaller weight falls into the law of diminishing returns IMHO.

I marked the heavy spot of my Ninja 500 wheel and lined up the yellow dot on the Dunlop 501. As I mentioned before, the actual heavy spot was about 100 degrees off from the valve stem.

The happy result is that the tire and wheel assembly is perfectly balance with zero weights.

I marked the heavy spot of my Ninja 500 wheel and lined up the yellow dot on the Dunlop 501. As I mentioned before, the actual heavy spot was about 100 degrees off from the valve stem.

The happy result is that the tire and wheel assembly is perfectly balance with zero weights.

Good info. I'm definitely going to do that the next time I have a tire off.

The tire dots can mean the light spot, heavy spot, or nothing at all to do with weight. Heavier place(s) in a tire can be seen inside the carcass, where belt ends overlap and extra thick rubber placed. There may be more than one overlap area, in which case a point midway between would be the heavy region or side of the tire.
A rim with TPS gear would be heavy at the TPS, unless grossly mis-cast.

On Michelin's its the bar code that's the light spot.

On my C14 the TPS is the heavy spot on the wheels.  Both sets of my PR3s did not have a dot on them.  I mounted the tire several times in different positions to find the spot where I needed the least weight.

Both sets of my PR3s did not have a dot on them.

It's the bar code on the Michelin's.

I did not know that.  Thank you.

It's the bar code on the Michelin's.

I went through this exercise with new PR2s I recently purchased. Mine had yellow bar on the front and none on the rear. I called Michelin's US tech support to ask what the scoop is. I left a message on the first call asking the question. I later called again and spoke to a person. The answer was that Michelin stopped marking their tires years ago when they switched from bias ply to radial. The manufacturing process is controlled to the point that weight differential around the tire is negligible. The yellow mark was suspected to be a distributor's inventory control method.

I did receive a return call from the message that I first left on the first call. I got exactly the same story. There is no mark on Michelin tires that indicates a heavy or light spot.

Mark

I just put a PR2 on the rear of the bike and it had the same embedded black and white bar code the last 2 sets of PR3's had on them. As to that being the light spot, it is what I read on this forum. But if you got confirmation from Michelin that they do not mark the tire than that's very interesting.

I just put a PR2 on the rear of the bike and it had the same embedded black and white bar code the last 2 sets of PR3's had on them. As to that being the light spot, it is what I read on this forum. But if you got confirmation from Michelin that they do not mark the tire than that's very interesting.

Talked with a crew chief from a racing team who's has a Michelin truck back up to their pits and off loads several sets for each race. I asked him when we were installing my PR3's and he said without question it's the barcode. Wishing now we wouldve balanced a bare rim now too. Next time for sure and will ask him to qualify his claim..If I get the nerve

I just put a PR2 on the rear of the bike and it had the same embedded black and white bar code the last 2 sets of PR3's had on them. As to that being the light spot, it is what I read on this forum. But if you got confirmation from Michelin that they do not mark the tire than that's very interesting.

Given that I got the same response from 2 trusted sources, I would have to believe it's true. Not only 2 sources, the first call was to the Michelin motorcycle tire specific tech support phone number and the second call was to the general support number (got tired of waiting for the MC tire guys to respond). I don't recall the exact physical location of each except the motorcycle tire support is in CA and the general support was somewhere else. I asked specifically about the locations to get an idea if these 2 people were sitting next to each other repeating the same scripted response. Apparently not the case.

So I am convinced. If somebody has a more compelling story that points in a different direction, I think we would all like to hear about it.

Mark

I will chime in, as much as I hate tire threads.

The bar code several years ago was the spot.
However, that has changed. I have heard from two Michelin Reps that the bar code is only for tire tracking through production.
Michelin boasts that their production process is so accurate that there is no heavy or light spot. The tires are perfect.

I have somewhat proven this.

If you balance the wheel.
Then mount the tire, IF you need weight it will oly be .25oz. Key word is if.

I use a Snap-On Computer balancer.
Not some home made static balancer with a lot of guessing to gain my results.

I will chime in, as much as I hate tire threads.

The bar code several years ago was the spot.
However, that has changed. I have heard from two Michelin Reps that the bar code is only for tire tracking through production.
Michelin boasts that their production process is so accurate that there is no heavy or light spot. The tires are perfect.

I have somewhat proven this.

If you balance the wheel.
Then mount the tire, IF you need weight it will oly be .25oz. Key word is if.

I use a Snap-On Computer balancer.
Not some home made static balancer with a lot of guessing to gain my results.

Good info. Next time I will balance the wheel as close as possible without a tire. Since I only run pilot roads now I shouldn't have to add much weight.