Permissible Wheel Balance Limits on R12's

I learned something new to me today while prowling through the RepROM disc for some other info.

BMW publishes allowable out of balance limits for the front and rear of my 08RT. The front balance tolerance is 5 g and the rear balance tolerance is 25 g. Up to 80 g balance weight is allowed, an amount that would make me very uncomfortable because one clearly has one or more badly manufactured components at that point (most likely a tire creating most or all of the problem).

For those metrically challenged, for round numbers there are 30 g per oz.

This clearly shows that balance tolerance is much more important on the front- in fact a factor of 5X as important according to BMW numbers.

What I learned is that's a bigger difference than I expected. 2X or 3X wouldn't have surprised me. Fronts are more balance sensitive on everything else I own.

A 5g balance tolerance is also VERY SMALL, too small to readily detect in normal riding by most, and getting any tire to stay in that sort of limit over its life isn't likely without rebalancing at some point in my experience. I'll bet almost none of us rebalance tires during their life though that 5g tolerance suggests doing it somewhere before mid tire life on the front. I've never rebalanced a tire on any bike I've ever owned since I learned to ride in the 1960's, for example. The rear value of 25 g can be maintained throughout tire life fairly easily and does not suggest the need for periodic rebalancing of the rear.

Any thoughts from service guys or others seeing this thread? Is the BMW spec a bit of smoke for the real world or is a periodic front balance something we ought to be doing? Is it worth the time and trouble to pull, balance, refit? Why?

With apologies to the Bard, "To bead or not to bead?" IS NOT the question, despite tangential relevance.

I have only re-balanced car / small truck tires to help diminish shake rattle and rolls with some success. Helped some, but loose suspension was probably real culprit on the cage.

On the same balancing subject, after I took delivery of a new 2009 R1200RT, I noticed there were no weights applied to the wheels. At the 600 mile service, service tech said it was not really important. I then bought the rear wheel adapter and static ÔÇ£re-balancedÔÇØ them myself. Front took 10g, rear 60g on the stock Bridgestone BT020. Out of spec per the manual, but only a slightly noticeable improvement due to low break in speeds.

Ken E.

No Balance guy

My last 4 sets on my GSA1200 get no balance and have not needed it. I mount my own, with tire machine in the garage. I've been using Bridgestones BattleWings and TrailWings and the tires come with spots defining the lite/heavy spots of the tires. I simply line these dots with the stems and move on, with no balance required on my last several sets of tires. I also think many tires find their own balance with a few miles on'em. Rebalance would suggest this too. Anyhow, I'm completely satisfied with the no balance solution I've found. I ride to 80mph and rarely any faster, if this means anything. Randy

Randy - have you checked the balance on the tires after aligning the dots - or is it you just don't feel any vibes?

I've never had tires that were balanced with no weights when tested on a spin balancer... and that's with carefully aligned dots/valve-stem on tires that still have the dot. Michelin PR2's don't have the dot, meaning either they found it insignificant or unused OR they make perfect tires every time (or only sell the perfect ones..) What is interesting is to check the actual rim balance with no tire on the rim. I've found the balance weight position with and without a tire ends up in the same general area, which indicates to me the rim imbalance is more significant then the tire imbalance.

YMMV - as may your balance experience.

deilenberger said:

I've never had tires that were balanced with no weights when tested on a spin balancer... and that's with carefully aligned dots/valve-stem on tires that still have the dot.

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Have you checked the balance of your wheels without tires? Aligning the dot to the valve-stem only makes sense if the valve-stem is the heavy spot of the wheel as it is assumed to be. My wheels (GS alloy, not spoke) came from BMW with the heavy spot almost 180˚ from the valve stem. If I did the normal dots/valve-stem alignment on those wheels I'd be exacerbating the out of balance condition.

I wound up balancing my wheel, including moving the after market tire pressure monitor sensor I added around until I needed the least amount of weight. Now, when I mount a tire I find that often I need not add any extra weight.

+1 on the importance of the actual wheel balance.

I've measured both rims w/o tires: my front rim is 1/4 once "heavy" within 1 inch of the valve, the rear is almost a full once out at about 75 degrees from the valve. For those that do their own balancing, I think it's worth the effort to measure and mark your bare rims and mount tires accordingly.

Supposedly, Michelins w/o markings are less than a 1/4 once out of balance. In two sets of PR2's, I've never had to add weights to the front and never more than 3/4 once to the rear.

On the other hand, on three sets of Roadsmarts, I've never used less than an once front or rear. I had one rear tire with two "dots" that ended up taking 2 onces to balance. Obviously, Dunlop's mfg process produces tires far less symetrical than Michelin. Even so, I prefer the Roadsmarts.

marchyman said:

Have you checked the balance of your wheels without tires?

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Really gotta ask - did you READ the rest of my posting before replying? I'm guessing not since in the same posting I said:

Me said:

What is interesting is to check the actual rim balance with no tire on the rim. I've found the balance weight position with and without a tire ends up in the same general area, which indicates to me the rim imbalance is more significant then the tire imbalance.

Click to expand...

BTW - who sez the dot indicates the heavy spot on the tire? I've always heard it indicated the light spot. Documentation from a tire manufacturer would prolly be illuminating.

deilenberger said:

Really gotta ask - did you READ the rest of my posting before replying? I'm guessing not since in the same posting I said:

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Arrrrgggghhhh! Apparently my reading skills have deteriorated in my old age. Or I got impatient and answered before reading the entire post. Looking back I think your guess was correct and I stopped reading somewhere after you mentioned the PR2. Sorry.

deilenberger said:

BTW - who sez the dot indicates the heavy spot on the tire? I've always heard it indicated the light spot. Documentation from a tire manufacturer would prolly be illuminating.

Click to expand...

I dunno, who? Wasn't me. I wrote about matching the dot to the valve-stem which is the assumed heavy spot of the wheel (not the tire).

Metzeler says:
at http://www.us.metzelermoto.com/web/products/technology/faq/default.page

The PR2s in my garage have no dots, previous Roadsmarts had a yellow dot and Metz uses red dot(s) as noted and is the only brand I've seen that sometimes has more than 1 dot. Forget what was on the Bridgestones- might have been green but not sure. Don't think most makers use number of dots to indicate a weight, just the spot that goes near the stem (tires light spot) but again don't know for sure.

Still would like to know the answer to one of my original thoughts- why is the front balance tolerance so darn small (about 1/6 oz)? Back when I mounted all my own tubed tires, I never balanced anything on front or rear and never noticed a problem though a lot of those bikes had enduro tires or knobbies. I am also fairly certain none of us could pick a tire only 1/6 oz off on the front just by riding on normal surfaces. Does anyone have any idea why the BMW tolerance is so tight? Obvious possibilties include it as a minimum detectable by the most expert rider or mechanical balance device, possible impact to tire life or wear on some specific bike component, etc. I don't know and would like to.

You can bet any tire you take off at end of tread life will be more than 1/6 oz out of balance even if it was in perfect balance originally. And the value makes clear the adhering to proper mounting practiceon the front can matter - that means first popping the beads to seal, then deflating, installing the valve core and reinflating- that give the best possible roundness/balance if the bead is properly lubed.

FWIW, BMW now sells weights in 2.5g increments. Used to be 5g.

Racer7 - (whatz'er name?)

As a WAG - it's because the front is more prone to cupping? And has movement freedom in two planes where the rear only has one plane of movement freedom.

Certainly on autos - the front is more "critical" then rear balance (ie - easier to feel a front imbalance due to the more "free" suspension and more components that can develop looseness..)

Be a good question for BMW - dunno who to ask though..

That 2.5g must be a record for low available weights. That's only half the weight of a nickel.....

Geez- am I going to have to back to doing my own just when I was getting lazy enough to let that nearby shop do them for me..

Bridgstone/Yellow dots;

On the BattleWings and TrailWings, the dots are yellow. I don't know all about checking the rim first for balance. I've not done it. All I do know is these tires don't need balanced on my bike, for a LOT of tires now. In my last several years, I've used Metzlers Tourances and BS above tires with great results, no balance on any of them. I must be a lucky guy, because I read here almost everybody still does the balance thing and I'm asking why, when I'm on the other side of the fence, looking in. Randy