I expounded on this in threads in the past but recently it came to the forefront of my mind when I was reading an article in one of my motorcycle magazines. It was a technical article that discussed the relationship of wheel weight and polar moment of inertia. Now before you say, oh boy, KPV is at it again, this will be very simple and straightforward and has real world applications. Read on.....
Everyone is concerned about "Unsprung Weight". They are correct in their efforts to try to minimize it. What people do not pay attention to is the polar moment of inertia of the wheels they choose.
Polar Moment of Inertia (PMOI) is, in layman's terms, the wheels resistance to turning from rest. That said, the lower the PMOI, the faster the acceleration!! We all like the sound of that!
A wheel's PMOI is determined by its geometric makeup. Basically, how much metal is in the rim section and how much metal is in the spoke and hub sections. We could call it the distribution of weight in a wheel's construction. The goal is very simple.
Put as little weight out at the rim as possible. This is why I have repeatedly preached to choose wheels that have spokes that taper from thick at the hub to thin at the rim.
For two wheels of equal weight, the one with less of its weight near the rim will accelerate faster because its PMOI is lower.

This can actually be tested very simply.

If several wheels could individually be mounted on a short axle and the axle supported on 2 sloping surfaces, all one has to do is put 2 marks on the slope and measure the time it takes the wheel to go from one mark to the other from rest. In this test, gravity is providing the acceleration force. The faster the wheel from A to B, the faster the wheel will accelerate on your car.

Voila!!!

If there is any wheel dealer out there that wants to carry out this experiment on various wheels I would be glad to provide telephone engineering support.

Hope that helps some of you with wheel decisions.

 

That's very interesting...I've also been told that by one of my friends who is a physics professor and car nut.

Maybe I'll give it a try with my 19" HRE's and stock 18's...I guess I'll go look for some parts to give it a try

 

Chris,
I am very interested to see your results.

 

Very interesting!!!! It appears your wheels fit that criteria very well...See u tomorrow w/ Evan...

 

R,
I practice what I preach.

 

Ken, yes, dead on on PMOI. Total unsprung is also obviously critical.