So with the tip from Chaz pointing me in the right direction, I did a little more digging. In MA, the DMV regulations pertaining to vehicle heights (for lifting and lowering) are set forth at 540 CMR 6.00. Here's a link:
http://www.yankeetoys.org/Documents/CMR6.rtf
These regulations also regulate "wheel track" which is defined as "the shortest distance between the centers of the tire treads on the same axle. On vehicles having different axle widths, the measurement shall be made on the widest one." 540 CMR 6.04(3) states: "The wheel track may be increased by the use of tires and rims for a maximum total increase of four inches beyond the original manufacturer's specification.
The use of spacers to increase the wheel track is prohibited. Fractions shall be excluded in all measurements and final calculations." The word "spacers" is not defined. Maybe I'll try to convince them that Spidertrax are "adapters," not "spacers."
Oh, and as Taxman said, don't rely on the ramblings of a nitwit like me for your legal advice. This is just some stuff I dug up while eating my lunch. On to your regularly scheduled programming.