I must be reading it wrong...this is copied from 2015 rule book :
I read this as it saying SPACERS are allowed, and must be .25 (1/4") thick maximum...
" (paragraph)13.4 Wheels
Any type wheel may be used provided it complies with the following: it is the same width and diameter as standard, and as installed (including wheel spacers if applicable) it does not have an offset more than +/- 0.25 inch from a standard wheel for the car. The resultant change in track dimensions is allowed. Vehicles originally equipped only with 12 inch diameter wheels, may use 13 inch diameter wheels of the same width as standard and offset within +/- 0.25 inch of standard.
Wheel spacers are permitted, provided the resultant combination complies with the offset requirements of this section. Wheel studs lug nuts, and/or bolt length may be changed. "
What did I miss ???? The specifically SAYS spacers, and no mention in the paragraph on adapters. If your trying to say if its not mentioned its legal, are you allowed to add a booster jet turbine engine on the trunk for straightaway speed....
nothing in the rules on jet engines.