If you are looking at the following two combinations:

x" wheels that weight y lbs. each

x+1" wheels that weight y-1 lbs. each

Which one will have greater acceleration?

I want to believe there is more to acceleration/wheel weight relationship than just "weight"

 

In the most basic of form; the combo which places the weight (or MOI-- Momment of Inertia) out the furthest from center line will be the one to cost you the most peformance loss. Are they all measureable? In many cases I'd guess probably not without some major differences, which 1lb is not.

 

The wheel/tire combo with the smaller diameter will always accelerate quicker (assuming weight is similiar).

 

Let's try to get a more realistic example. I've actually been thinking about this myself. Lets say I have a stock '05 MC with the R81 7-hole 15" rims at 12 lbs. each. Let's assume the tires weigh 20 lbs. each for 205/60/15.

How much would it affect acceleration if I switch to a Mille Miglia Spider II rim weighing 22.5 lbs. combined with a tire weighing 24 lbs?

In short, would 14 extra lbs. or so at each corner make a noticeable difference?

Thanks,

Joe

 

Yes it will make a huge difference. You would not be nearly as quick off the line. You would also suffer longer braking distances.

 

Would you add 30% more weight if you had a choice?

 

32 pound 15" wheels vs 46.5 pound wheels?

Not much of a comparison. In a lower powered MINI like an MC it will be like night and day. The lighter wheels will feel nimble and work just fine, the heavier wheels will make you drag along like you lost alot of power. You'll accelerate slower and take longer to stop with the heavier wheels.

For:
If you are looking at the following two combinations:

x" wheels that weight y lbs. each

x+1" wheels that weight y-1 lbs. each

Which one will have greater acceleration?

Lets pick a lightweight example.
15" wheels that weigh 10.6 pounds like Kosei K1 TS vs
16" wheel that weight 9.5 pounds like SSR Comps.

In this case with both wheels mounted on the same tires with almost the same outer tire diameter and used on the same MCS then the lighter 16" wheel would perform better. But the difference will be really small.

Now lets pick a heavy example.
17" wheels that weigh 25.1 pounds like stock S-lytes vs
18" wheels that weigh 24 pounds

Using the same type of tires with roughly the same outer tire diameter the two wheels will perform about the same. The powerful MCS will do OK but the less powered MC will be at a disadvantage and not be so quick.

Another point is in reality when you look at tires in the 15" sizes they are relatively light about 20 pounds each and when you look at tires in 16", 17" and larger sizes the weights start to creep up by 1-2 pounds for each 1" increase in diameter or for taller side walls.

This means that the smaller wheel fits on a lighter tire while the larger lighter rim fits on the heavier tire. The total package is about the same weight but the tire is lighter in the smaller wheel which is a plus for acceleration. The rubber compound and tread design are important in helping with traction so lightness of the tire is not the only variable for good acceleration- you don't want wheelspin.

In your equation the difference in weights of only one pound is too small to make much of a difference.

My wheels are:
R90 17x7" at 24 pounds
Centerline RPM 17x7" at 14 pounds
Kosei K1 TS 15x7" at 10.6 pounds

Each lighter wheel works much much better even with relatively good tires on each. The less power you have the more you'd appreciate the lighter wheels.

 

School said:

F = m a

where;

F: Force
m: mass
a: acceleration


This calculator from 1010 Tires will help ya see if it whether they're 2 fast or 2 slow

http://www.1010tires.com/TireSizeCalculator.asp

 

I see these threads all the time - and people throw around terms around all the time without any quantifiable numbers.

Who has any numbers to show exactly what the differences are? What are we talking 0-60 differnce here - 0.1 seconds? 0.5 seconds? 1 second? How about braking - 5 additional feet? 20?

I think a lot of people hype this up without know exactly what they are talking about. Let's see some performance charts.

 

I'm sure you can come up with a quick answer if you run it with the same wheel and same tire, one at 15", the other at 16".

However...the issue is not only the weight of the wheel OR tire but WHERE IT IS AT. That's the MOI that I spoke of earlier. To get that data you'd need more than a quick formula. Huh? Suppose one wheel has a skinny five spoke design to it, the other a more closed look and fancy mill work. The weight is not at the same point.

Same thing with tires- those run flats you love to hate are the same size let's say as a race tire. The race tire is light we all know. But it's not only the weight it's the fact that it's out so far from centerline. A 15" run flat may net the same numbers as a 17" standard wheel and tire package.

This is the same reason clutchs and flywheels are small. And alum ones have a steel ring gear with holes in the alum then some nifty 5.5" dbl disc Tilton in the middle. It's less power to spin it up and less inertia when spinning. So it slows faster too.

 

Yes, and no. You will have to accelerate the smaller diameter wheel/tire
more to get the MINI up to the same speed as the larger wheel tire, so
it evens out (talking about the diameter of the tire being larger or smaller)