Just to show some #s on weight change, since #s are better than
buttdynos:
New Super Chevy has an article on a new SS they have been modifying. This month they dropped the wheels and brake size. They wanted 17s on it to use tires with more sidewall. As with most mods, there is more than 1 change happening so it is not exact apple for apples. Here is a summary.
Front:
Removed
OE cast front wheels: 20x8, 245/45/20 PZero - 64 lbs each!
OE front 14" brakes
Added
4th gen front brakes
New 17x4 Bogarts with 4.5/26-17 tires:
front wt savings - 100 lbs
(the skinny tire alone should help some with less resistance)
Rear
Removed:
OE cast rear wheels: 20x9, 275/40/20 PZero - 68 lbs each!
OE SS 2010 SS rear brakes
Added:
2010 V6 rear brakes
17x9 SLP 4th gen 5-spokes and 274-40-17 hoosier d/rs - 34 lbs each
rear wt savings - 82 lbs
Total wt savings - 182 lbs - all unsprung
Running at atco they dropped:
60' time by .06 (1.86-1.8)
1/4 ET by .19 (11.81-11.62)
MPH up by 2.06 (199.27-121.33)
(last test used nitto 274/40/20 d/rs, so the trap gain was not all tire)
Those OE sizes are ridiculous. But I digress.
It appears no one makes 'skinny' 18s to clear the OE 14" rotors, thus the reason they killed the braking on this boat. De-braking is not for me! Especially in a 4000 pound car driven on the street.
I think the technical term is MOI - moment of inertia. Can any of you engineering students maybe expand on this? My humble knowledge is it takes more energy to get a heavier wheel moving and more energy to stop a heavier wheel. So there is zero question lighter is better.
So the practical question is saving a few lbs on a street only car really worth it? Probably not. Unless you are shedding a big pile of weight. Is it worth it on a car that is regularly raced - drag or auto-x? Sure.