Rolling Mass

JLawton

JLawton

New member
I need to get a pair of wheels for next season. My choices are the stock VW wheel which are CHEAP and easy to find or a two pound lighter, more expensive wheel (I have a full set of each, I just need another pair to rotate the Hoosiers on).

How much impact is that two pounds going to make? For a racer on a serious budget (small), I really need to see a benefit before I lay out the cash. Any hard data?
 
Speed costs money...how fast do you want to go...?

Actually, Hoosier seems to keep changing the weight of the tires so I would not worry about the two lbs. if you cannot afford the light ones.
 
Jeff,

As I did the budget for the SM to ITA conversion last month, I included two sets of SSR 15x7's. Just under $300 each. Currently we run 13lb wheels on the SM's and these are just under 9 @ 8.8lbs. I asked our new Team Engineer (with IMSA, CART, etc experience) on our Pro Miata venture, what he thought of the expense...he laughed!

4lbs of unsprung weight (UW) for the difference of about $180 per wheel...that is $45 per lb of unsprung weight per corner.

NO BRAINER he said. That kind of reduction is critical. I think it also depends on what shocks you have. Less UW allows cheaper, more off-the-shelf- shocks to control your suspesnion better. Less UW allows ANY shock to control the suspension better but you get the point...the Miata will get teh Advanced Design units to start...

YMMV. No hard data, just theory. It's easy to spend someone elses money! :D

I would buy the light set.

AB
 
Originally posted by JLawton@Nov 3 2005, 02:09 PM
I need to get a pair of wheels for next season.  My choices are the stock VW wheel which are CHEAP and easy to find or a two pound lighter, more expensive wheel (I have a full set of each, I just need another pair to rotate the Hoosiers on).

How much impact is that two pounds going to make?  For a racer on a serious budget (small), I really need to see a benefit before I lay out the cash.  Any hard data?
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Actually, I disagree with the previous post. Unsprung weight (2lb x 4 = 8lb) is a significant matter. Especially so with a car that is low powered like most of our IT cars.

Costs set asside (just theory NOT reality for most of us) heavier wheels and tires are, harder to stop, harder to accelerate, harder to control with shocks/springs and have more of a tendency to self center (resist steering input).

I always race on my lightest wheel/tire combo (Welds). I practice on my next lightest combo (Tridents) and use my heaviest set (Mullins) for rains.

In my case there is a 24lb difference from lightest to heaviest. This would be VERY significant and affects ballast and braking points.

If you can swing the lightest setup you'll be very happy.

Travers
 
Jeff,
You should hold out and try to find a set of wheels that are more than just 2-4 lbs heavier than what you have.
Heavier is stronger, and stronger is more reliable, so go ahead and find the heaviest wheel you can. Think of the money you will save in the long run when you don’t have to replace the light weight wheels so often…. if you need help in this department I would gladly offer my time to help you find some steel wheels, or if you are hell bent on the weight issue you could just run a narrower wheel. That would even provide less rolling resistance.
Boy am I full of good ideas for my competitor or what!!!!

Matt Bal
 
From a hassle stand point, having wheels that don't match one another is a pain. Having 12 identical wheels is really nice when you have to start shuffling them around, unless you like mounting & dismounting tires a lot.
 
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