Yes, it is REALLY true, but like you, Kevin, I think the effect is blown out of proportion by many people on this board. Every time somebody asks about or posts pictures of a new wheel, the first questions in reply are, "How much does it weigh?" and, "How strong is it?"
My street wheel/tire combo is a set of 17x7" UK WRX wheels with 215/45-17 Toyo T1-S's. The UK wheels are supposed to weigh around 17.5#, and the Toyos weigh 20.1# (according to Toyo's website), so we get roughly 37.5# together. My auto-x/track wheel/tire combo is a set of 15x8" Volk TE-37s with 225/50-15 V700 Victoracers. The Volks are supposed to weigh 9.5# each, and Kumho says the V700s weigh 23.8# each - for a total of 33.3# all together.
Not only is the race setup over 4# lighter at each corner, but I also get a 4.7% gearing advantage by using the shorter tires. Guess what? I can't feel any sort of acceleration difference with the ol' butt dyno. I think someone would have to be really in tune with their car to feel a 4 or 5# difference.
Pat Olsen
'97 Legacy 2.5GT sedan