[Lifted07Duramax]

Right section for this question?

Would I see a bigger improvement in performance from dropping 20lbs of body weight or 20lbs in overall wheel weight. So 5lbs less per wheel.

Im thinking more noticeable from wheel weight since its less weight to turn to get moving? But then again will I have a bigger issue with traction.

[VTECaddict]

You will notice a bigger difference in reducing wheel weight (unsprung rotational mass).

[Lifted07Duramax]

Originally Posted by VTECaddict

You will notice a bigger difference in reducing wheel weight (unsprung rotational mass).

I don't know if you would know or if there is even a calculation to figure this out but what would 20lbs dropped of all 4 wheels be equal to in body weight?

Reason I ask is because Im thinking of going with Forgestar F14s and it looks like they are about 6lbs lighter a piece than my Series 199 OEM wheels. Hell could be more than 6lbs each. Hard to find exact numbers on my wheels.

[BavarianFanatic]

Google "unsprung weight". You'll find volumes on the subject. And, yes, shedding unsprung weight will have far more effect than an equivalent amount of sprung weight.

[Lifted07Duramax]

This says unsprung or sprung is all the same as far as 1/4 times
http://victorylibrary.com/mopar/sprung-c.htm

[-Wingman-]

Not sure how to calculate that. Try running lap with a 20 lb vest, then try it again with 20 lb ankle bracelets. Report back.

[Lifted07Duramax]

Originally Posted by -Wingman-

Not sure how to calculate that. Try running lap with a 20 lb vest, then try it again with 20 lb ankle bracelets. Report back.

I don't see how that makes sense here, but I could run the lap faster with the vest vs the ankle bracelets.

[thenewrick]

Wheel weight doesn't affect just acceleration but also braking, handling, ride comfort. A general rule of thumb is 1lb of un-sprung weight= 4lbs of curb weight. You must also note that wheel diameter/width and tire diameter/width play a big part as well. Generally you want the smallest/lightest/thinnest wheels and tires with the most grip. If you have too much power and are easily braking loose wheel traction you'll want a wider tire.

The first thing I do when I get any car is change the wheels and tires, it makes a big difference, especially in BMW's because the stock runflat tires are truly awful.

[VTECaddict]

Originally Posted by Lifted07Duramax

This says unsprung or sprung is all the same as far as 1/4 times
http://victorylibrary.com/mopar/sprung-c.htm

It's really more of rotational mass vs non-rotational mass, not sprung vs unsprung. Unsprung rotational mass makes the biggest difference because it requires less force (power) to spin. So things like wheels, tires, brake rotors, axle shafts, etc.

Non-rotational mass will have basically the same effect on straight line performance whether it's sprung or unsprung, but unsprung non-rotational will have a bigger effect on handling than sprung non-rotational.

[WreckerX5d]

Get the wheels. The 20+lbs loss in wheel weight will have a greater advantage than the 20lb of chassis weight. MPG, throttle response, WHP (less drive train loss), and handling will all improve at a greater effect than the other.

[CombatNinja]

Pay more attention to the weight of the tires than the wheels. The tire is farthest from the axis of rotation and therefore has the greatest effects. I see lots of people drop $2000 on light wheels only to put back more mass with the tires they choose.

[Ivan@PYSpeed.com]

Originally Posted by VTECaddict

You will notice a bigger difference in reducing wheel weight (unsprung rotational mass).

[jwalker87]

Rotating mass > Unsprung mass > Sprung mass