Wheel and tire weights

[vitalc]

A few weeks ago I was browsing the forum to find info on wheel weights for the R1100S stock v. PVM forged alu. I couldn't really find it. My apologies if I'm beating a dead horse.

The naked PVM (5Y) front wheel weighs 3930 g
Two disks, ABS ring and bolts add 2810 g (bolts alone : 188g)
Adding a Pilot Road 2 adds 4460 g. That's right, the tire weighs more than the wheel.
Total 11200g or 11.200kg

The stock front wheel with disks and a fairly new Z6 weighs 13.260kg. My guess is that the naked stock wheel weighs a bit over 6 kg

Say you find extreme lightweight wheels (CF or forged Mg), that weigh half of the stock wheels (weight loss: 50% of stock). Mounting similar disks and tire on both, will reduce the total wheel weight loss to <25% of stock. Also remember that most of the weight sits at the very periphery of the turning wheel: the tire; hence, no risk for instability because of light wheels.
Still, light weight wheels significantly decrease the force needed to change direction.

The PVM (5Y) rear weighs 4640 , the rear PR2 tire adds 6400g. I haven't taken off the stock yet.

Tires may significantly influence maniability both because of their profile, and because of their weight. The difference between front tire weight (sport tires, same size) for different brands can be more than 10%. Also 120/65 tires may cut the 120/70 weight by >10%.

For info: I used digital scales with a precision of 5 g, and I found weights of other tires in PS magazine.

Karel

[tm1100s]

Do a search on the PVM wheels in this forum. I did all this for wheel weights (stock and PVM), a couple of different tires and different brake disks way back for our group buy. I still have the info around here somewhere.

[wswartzwel]

Here is the thread

Wheel/Rotor Weights - Info

[vitalc]

Most helpful, thanks

Karel

[markjenn]

I'm not an expert, but I always understood that the big advantage of lighter wheels was not to reduce the effort for direction changes, but instead was to reduce unsprung weight which better allow the wheel to follow the road by reducing the energy that needs to be stored and dissipated in the suspension while following bumps. And in this regard, even a 10% reduction can result in a noticeable improvement.

- Mark

[roger albert]

It is BOTH. But you're otherwise right Mark. Even that 10% reduction is readily noticed.

[vitalc]

Mark,
What counts is the proportion unsuspended to suspended weight that makes the difference. The heavier the bike (+rider), the better tire contact (wheels remaining the same). So yes, lighter wheels will improve the ratio. However, I think what the average rider readily notices with lighter wheels is how easy the bike flicks from one side to the other. I doubt most riders would feel the difference in tirecontact or suspension work.
On a R1100S the unsuspended to suspended (included rider) ratio is roughly 1 to 10 (65 / 650lbs). I don't notice that my suspension is smoother when I have, say, a full tank and some luggage (as compared to 65 lbs less). Likewise I wouldn't notice a smoother ride when my unsuspended weight is 10% less.
Karel

[bradzdotcom]

tire weight can make a big difference all in itself.
i was watching a tv show (top gear?) and they were testing a supercar.
although the car was identical to last year's offering, it was about 12 mph slower on it's 200+ MPH top end.
the only difference was the tires. they'd switched brands and even the rep from the car company said it would go right back to it's original top end speed with a simple tire change.

my bike has carbon fiber wheels and it made a significant difference in response and "flickability".
also, because of the lower unsprung weight, it took a lot of suspension fiddling to get the bike set-up correctly. the lighter wheels required that i slow the suspension waayyyy down.

[bacn5]

I just painted my rims and was considering using Dyna Beads to balance the tires... Anyone have any experience with them?

[markjenn]

Originally Posted by bacn5

I just painted my rims and was considering using Dyna Beads to balance the tires... Anyone have any experience with them?

A lot of folks report good results, but you can say the same for fuel magnets and tornado intake vortex generators. Personally, I've a very skeptical person on things like this, but the principle of this product -- that an out-of-balance wheel will wobble enough to distribute the beads to the lighest part of the wheel -- has some limited merit. But I'd still like to see some solid testing by someone other than the people selling it. And their "soda bottle" demo is so wildly different than a real wheel in rigidity than I don't think you can place much credence in this. It reminds me of the demos for the vortex generators that turn a soda bottle upside down and it empties faster with the vortex installed. Makes for good TV, but doesn't mean squat.

I'll keep balancing conventionally, but I would never say unequivocally that this product doesn't work.

- Mark

[roger albert]

> I'll keep balancing conventionally, but I would never say unequivocally that this product doesn't work.

Me either. So, how would I best express an opinion one tiny iota short of that?

[wswartzwel]

One of my customers asked me to install some of those things... I said no way... He showed up with a tire and a package of them. After installing them I put the wheel on my computer spin balancer.... I spun it 5 times... 3 of those 5 showed balanced, needing zero weight. The other 2 times it was off .75 and .5 oz. He likes them. I would not use them...... even if you paid me.

[roger albert]

I've done the same drill, and also refuse them. What starts out as balance mass can become unbalanced and visa versa if it's free to move. I'm pretty sure I've seen it in my own washing machine. Seriously, the results were all over, and that was true even using a horizontal method (bubble balancer)