Originally posted by tboner:
Doesn't a lower profile tire have to have a thicker sidewall to support the same amount of weight?
Well, to make this a fair argument we have to assume that we're using the same model of tire from the same company with the same type of material properties and tread patterns. Given this ideal situation, I'm not sure! lol
I would think it would have to have an even thinner sidewall because it's not as tall (thinking of the stability of a tall skyscraper versus a short building having the same width). I don't know if you can put it as easily into those terms, though.
With the lighter wheel 18" (or any 18" wheel for that matter), you get a bit heavier tire. Even if you keep the width the same. Or at the very least, the distribution of mass is even more skewed away from the center of the wheel.
Assuming the same conditions as above, not necessarily. Depending on the height of the sidewall, a smaller diameter tire can have a greater radius of mass distribution. Let's take 2 tires for arguments sake, say a 215/60-R16 and a 215/35-R17. Without knowing all of attributes of the tires accept that they have the exact same tread pattern, material density, etc., let's assume that the average center of mass distribution is half-way up the sidewall. The outside diameter and sidewall height for the 16" tire is 21.08" and 5.08", respectively. Those same numbers for the 17" tire are 19.96" and 2.96". That would mean that the average center of mass distribution for the 16" and 17" tire are 18.54" and 18.48", respectively. So it's possible, but I agree not likely.
So given two wheels of the same mass, the one where the average mass point is further from the center of the wheel will have a greater moment of inertia.
Yes!
I've got to stop, my head hurts now.
So does mine.
