Not to be pedantic, but force, energy, and power are three different things.

Force = mass x acceleration: it's a change in momentum.

Energy = force x distance, or mass x speed^2; it is the same as work.

Power = energy / time, the rate at which one form of energy is converted to another.

Force is measured in pounds or newtons.

Energy is measured in joules or ergs or ft.-lbs.

Power is measured in watts or horsepower.

 

I think there is another factor at play here.

Yes, the lighter, larger diameter wheels may spin up more quickly that the heavier, smaller diameter wheels.

However the car is not in the air.

What about the change in gearing?

Think about a car with a gear change and no change in wheels/tires. The lower geared car is going to be faster in acceleration. Road Racing cars are often "slow" in the quarter mile despite their HP. Why?

Well if the gearing is taller, the acceleration will be decreased.

A larger diameter wheel is effectively changing the gearing. That is why the car is slower. My Miata had the same thing happen when the 15" wheels were on vs. the 14" stocks. 1" increase in diameter noticeably affected acceleration....not that there was much to begin with.

Reijo

 

^^But you're not changing the overall diameter if you go with lower profile tires. (Which everyone does)

 

Really good dicussion on wheel weights and Magician has the math down pat

Here's a couple of links to help with determining offsets and Tire/Rim diameter..

Wheel Offset Calculator

Tire Size Calculator

Hope they help....

 

Now I know why women have trouble with other women in the same outfit. Three sets of Volks is to many for Calgary. BlackS2000, I'd recommend anything but Volks.

 

great thread. i agree that the lightest wheel tire is desirable. you can spin things up very quickly as dave mentioned but also there is the inertia effect of trying to stop something that is heavy and spinning. one you will be on the gas alot the other will help you out in sustaining your momentum. in the end here is it durabilityvs cost vs bling based on perceived value?

 

Exactly! We are NOT changing the overall wheel/tire diameter.

 

[quote name='Calgarian' date='Feb 7 2005, 10:40 PM'] Now I know why women have trouble with other women in the same outfit.

 

Wow....looks like a lot of people are getting new shoes including me..18's....Can't wait until Spring to get out and stretch those legs...

 

The higher the gear ratio the greater the torque at the wheels. If you double the gear ratio you get twice the torque but you halve the speed.

You'll note that in my previous post I specified torque at the wheels. If you change the gear ratio, you change that torque, and thus change the calculations.