Quote:
Originally Posted by Socale92
sensation of power/acceleration loss from 18 to 19 inch rims is dramatic! caveat emptor  |
Dramatic might be over stating it just a little don't you think.
I would agree if you were talking about handling characteristics. A small/lighter wheel will readily move in response to road bumps and will have more grip when tracking over an imperfect road.
But as far as rotating mass goes, 18s to 19s would not be dramatic. You could be seeing max 3-4 hp gain, hardly dramatic.
The TV show Sports Car Revolution (SCR) took an Acura RSX and changed the tires/wheels from 15" to 17" and did a dyno comparison. Both sets of tires and wheels weighted about the same, so no change in unsprung weight. The end result was that with the 17" wheels the dyno measured 7 less horsepower at the drive wheels when compared to the 15" package. So with a two inch smaller wheel, they reported a max 7 hp.
You also have to take into account wheel design. All wheels have their weight distributed in different ways, due to different wheel designs. This will affect the whole rotational mass equation.