I have to decide by Friday.. I'm thinking I like the Bridge Spokes better but if the S-Winders are lighter.. I'll stick with those.

 

Or, you could just get the better looking wheel for your stockers and use for daily driving. Then get a nicer aftermarket light weight wheel for your track/autocross.

That's what I'll be doing. The only issue I have is who is going to buy my EVO MR.

 

Lighter wheels help just as much if not more in the real world with bump and holes than they do on smooth tracks. The s-winders look lighter to me so that's why I'm going with those.

 

Never heard of that before. Not sure how a lighter wheel would help with a bump or a pothole.

Light wheels are intended to reduce unsprung weight, allowing your wheels to turn with less power resulting in quicker acceleration and steering response. Smoothness of your road surface isn't as much of a factor. I would say wheel strength would be more significant for that. Forged vs cast alum.

 

Bridge-spokes weight 20.1 lbs according to MINI2.com.

 

Unsprung weight, exactly! The less it is, the easier it is for the car to keep the tires against the road with equal force. When you go over a bump the tire is thrown upward. The lighter the unsprung weight the less the suspension has to work to keep the tire on the road. Since the real world has more bumps than a race track this can really be noticed if you know what to feel for of have a heavy comparison wheel. The heavier the wheel/tire the less the car feels planted over irregular surfaces.

You are explaining the other reason for light wheels, not unsprung weight but rotational weight(there may be a better term for it). Both are reasons not to get heavy wheels just because of looks.

 

Just weighed my s-winders with 195/55 Goodyears. 40 lbs.

MINI2 has the s-winders at 22 lbs. and the tires at 24.4 or 46.4 total. My scale may be off a pound or two but not 6!

I hope the wheels are 16lbs.!

 

I hope they are 22lbs myself. That means I'd get better performance than I already have if I switched to a lighter wheel

 

[quote=inomis;1258847]Unsprung weight, exactly! The less it is, the easier it is for the car to keep the tires against the road with equal force. When you go over a bump the tire is thrown upward. The lighter the unsprung weight the less the suspension has to work to keep the tire on the road.


I don't believe the weight of the tire has got anything to do with the amount the suspension has to work to keep the tire on the ground - the suspension carries the weight of the car and any bump in the road will put additional force onto the suspension, which varies by speed and size of the bump (Force = Mass times Acceleration). As the mass is determine by what is sitting on the suspension, the weight of the tires makes no difference.

 

The tire is part of the unsprung weight and everything I've ever read says the lighter the better. The unsprung weight is the mass you want to move since the real world road is not flat and the tires need to stay in contact with the road. Having it as light as possible makes it easier to control.

Here's a couple of links to help you. Search for "minimize unsprung weight" for more.
http://www.edmunds.com/insideline/do...ticleId=104526
http://www.rqriley.com/suspensn.htm

 

Looks like the MINI2 site has a misprint. Tirerack has the GY 195s at 22 lbs and 24.4 diameter so I'm up to 18 lbs!

 

I agree with you that lighter is better and sure do appreciate you providing links to 'help' me, but the weight of the tires still has nothing to do with helping the suspension to keep the tires on the road, as much as it improves comfort, security, braking ability, l

 

I agree with you that lighter is better and sure do appreciate you providing links to 'help' me, but the weight of the tires still has nothing to do with helping the suspension to keep the tires on the road, as much as it improves comfort, security, braking ability, lower ratio of sprung vs unsprung weight , vibration etc ...

 

Lighter? Heavier? Just go with the bridge spokes - they look better!

 

I guess I don't understand what you are saying then. What does the does improving the ratio of sprung vs. unsprung weight do then? You say the mass of the car is what sits on the suspension. The whole car is the mass. The unsprung weight is accelerated first and if it's small in relation to the much larger mass of the sprung weight it will be easier to control than a large unsprung mass would be. The spring stores the energy and the shock controls the rate the energy is stored and released. The large mass remains relatively still and the smaller mass tends to stay in contact with the road. If you had a car with 90% unsprung weight and 10% sprung it would be next to impossible to keep the tires in contact with the road over bumps etc. Please help me where I have it wrong.

 

Hey everyone. I'm one of the deprived people up in the Pacific Northwest with a 4-6 mo wait for a 2007 MCS. Thought I'd add my 2 cents.....

A lighter wheel will return to the road quicker. A bump forces the wheel into the air. A heavier wheel/tire will want to stay in the air longer. (A body in motion tends to stay in motion unless there is an opposite force acting on it). The suspension forces the wheel back onto the road. Easier to do with a lighter wheel/tire. A race car with a suspension expertly tuned to keep the tires on the track will outperform the same car with a lesser suspension by seconds. Thats why all the top race teams have Shock dynoes to tune their suspensions.

As we all know, keeping your tires on the road optimizes your ability to stop and turn.

Hope I haven't confused anyone any more.

Mark

 

I don't know that this is true but I thought I'd add to the confusion.

Wouldn't a heavier tire want to return to the ground faster or at least not bounce as high?

g.r.a.v.i.t.y.


*shrug*

 

I think it's back to physics. A body in motion tends to stay in motion and a body with greater mass(I think mass is best described as weight times velocity) will resist changing its vector/direction of travel. For us that means a heavier tire, once bounced off the road will want to stay in the air longer(resist changing motion/returning to the road) longer than a lighter one. A heavier tire will resist changing direction off the road, but once it's leaving, it won't want to come back as quickly. That's why a great suspension makes a car faster that it's brother/sister car with an inferior suspension.

Gravity doesn't really come into play. 2 objects dropped the same distance weighing differently will hit the ground the same time, assuming wind resistence is removed from the equation. A pea and a brick will hit at the same time.

Boy, I need to drink less coffee and get back to the garage............

 

Now why did you have to go and clear that up?

 

Think you got that backwards - w=m*g thus m=w/g not the other way around.

Velocity is a measure of change in distance in a given direction, direction being the key differentiator between speed and velocity. Moot point as velocity or speed has no influence in this discussion.

Not disagreeing with your assessment. You probably also want to consider the rebound force from the spring also being applied to a larger mass vs a smaller mass. End result, lighter wheel, returns to road before heavier wheel.

 

Wookie,

Thanks for setting me straight. That's why I tried to put things "I think". I knew my assesment was correct, but also know that physics is not my strongest suit.

Mark

 

This all means I made the right decision... Bridge spokes are lighter than the Winders and 16s better than 17s... you made my day

 

It's still not clear to me that the Bridge Spokes are lighter and I tend to think they are not.

The as on car s-winders weighed about 18 lbs. vs the MINI2.com weight of 22.2 lbs . This was from a BMW document but it certainly seem wrong to me at this point.

Same could be true of the Bridge Spokes. Their weight was from the same document. Someone take them off and weigh them! I weighed the wheel & tire by itself and with myself to double check my scale. I'm sure I could be off a pound either way as my scale does not do tenths.

 

Inomis,

Your post makes it seem that you are stating that the tire/wheel combination weighs 18 lbs. Is this so? If that is what you are saying, you are wrong. Tires usually weigh 15-20+ pounds in the sizes used by Minis. Wheels probably range from 10 (maybe) to 20+.

In terms of the huge importance of unsprung weight it may clarify the issue a bit to move away from the idea of holding the wheel to the ground and think of the job of the suspension in a different way. A car's suspension system has the job of controlling the movement of the tire/wheel assembly. It is much easier to control a lighter mass than it is to control a heavier mass. So less unsprung weight means that the springs and dampers have an easier time. If they control the tire/wheel mass effectively the tire will spend more time in intimate, controlled contact with the ground. It's not so much a matter of pushing the tire down to the ground as it is reducing the variance in the amount of force that the tire "feels." Miniminizing variance makes for more consistent traction.

I hope all this helps. Suspension is a complex subject. Race teams pay lots of money to get the best suspension possible within the rules of whatever class they are in. A fair bit of the money goes to pay for ultralight tires and wheels.

Happy motoring,

Joe s

 

The winders look lighter - fewer spokes, with less metal. But the rim may be heavier to compensate for a longer span between spokes. Hard to say. Email the keeper of info at Mini2 and ask them where they got their info.