Smaller lighter wheels

[Trader]

I have attached a link to an excel program that calculates the effect that smaller and lighter wheels will have on acceleration.

It calculates the effect that less torque is lost due to rotational inertia from a smaller wheels. It then translates this into equivalent sprung weight (same effect as removing this weight from your car).

The results may suprise some of you.

The stock wheels are 18" diam. 24lbs with 24 lbs tires.

I entered a few different scenarios here all with the same tire weight.

Lighter 18" wheels (18 lbs)
Equivalent sprung weight = 77 lbs

Lighter 17" wheels (18 lbs)
Equivalent sprung weight = 115 lbs

Lighter 16" wheels (16 lbs)
Equivalent sprung weight = 170 lbs !!! ===> WOW!

Stock weight 17" wheels (24 lbs)
Equivalent sprung weight = 75 lbs

Stock weight 16" wheels (24 lbs)
Equivalent sprung weight = 80 lbs

So as you can see even with the same weight wheel as stock just changing the diameter can net you a performance increase.

 

[RelliMS3]

does that take into consideration that you will have to have higher profile (meaning heavier) tires?

 

[Trader]

No I assumed the tires were the same weight. If you look at tire rack which posts tire weights there is not much difference in them. But the excel sheet does let you enter a weight for the tires as well.

Take this tire for example:

THe Hankook Ventus R-S2 (which is what I was looking at)

http://www.tirerack.com/tires/Spec.jsp?make=Hankook&model=Ventus+R-S2&tirePageLocQty=

225/40ZR18 = 23 lbs

225/45ZR17 = 24 lbs

225/50ZR16 = 24 lbs

Not much difference. That seems to be the case with most tires. You would think there would be difference but maybe it is because of the reinforcing

 

[08cosmic3]

The wheels I'm going to buy are 17" @ 14lbs each. Thats 10 lbs off each corner vs stock.

 

[AWDthis]

Does 30 or 40 pounds really affect the car that much?

 

[drledford93]

Does 30 or 40 pounds really affect the car that much?

I am currently running 16" 3rd gen RX7 rims at 16# per corner and the acceleration and cornering difference is incredible. Must be seen to be believed...

Daniel

 

[08cosmic3]

Does 30 or 40 pounds really affect the car that much?

The 40lbs I'm taking off is off the rotational mass which magnifies the weight reduction. Someone plug in my #'s to the formula. Going form. 24lb 18" to 14lb 17"

I'm betting it will be like removing 250lbs form the car.

 

[Trader]

The 40lbs I'm taking off is off the rotational mass which magnifies the weight reduction. Someone plug in my #'s to the formula. Going form. 24lb 18" to 14lb 17"

I'm betting it will be like removing 250lbs form the car.

Lighter 17" wheels (14 lbs)
Equivalent sprung weight = 158 lbs

Lighter 16" wheels (14 lbs)
Equivalent sprung weight = 191 lbs