his [correct] answer is 1.5 to 2.0
http://www.miataforum.com/ubb/ultima...c;f=3;t=006390
after looking more closely at the s lites and finding out that the sidewalls of the runflats aren't as thick as i thought, my suspicion that my 18" diameter was a little low was well founded. my guess now is that the wheel tire mass is lumped closer to 20". so the chassis equivalent number is closer to the 2.0, say 1.8.
my point again, though, is that the ballpark number is in this range, NOT 4 or 6 or 10!!!!
glad you guys found this useful and fun!
