Here's the rules:
http://www.mass.gov/courts/docs/lawlib/ ... 40cmr4.pdf
And the 4-wheel drive specific calculations for Altered Vehicle Height (540 CMR 6.00) :
http://www.mass.gov/courts/docs/lawlib/ ... 40cmr6.pdf
Original Manufacturer's Height: The highest distance inclusive of the largest tires and highest suspension
available as standard or optional equipment for the particular vehicle from the original manufacturer.
The distance shall be measured between the lowest edge of the centerline of the operator's door, or
to the lowest point where the door would meet the body on vehicles without doors, or to the lowest
point on the floor panel directly below the operator's position on vehicles designed without doors, and
the level surface on which the unladen vehicle rests, as determined by the Registrar.
And lets not forget this:
6.06: Violations
(1) Due to slight variances in production tolerances, violations must be in excess of one inchbeyond
the Registrar's specifications of approved maximum altered heights.
I can't find the "Original Manufacturer's Height". Specs include axle clearance but the 'height' is measured with or without a top (hardtop, soft top, topless) but no specs on "the lowest edge of the centerline of the operator's door....... and the level surface on which the unladen vehicle rests"
) and this may or may not be accurate but a ride height of +/- 2 inches of the factory height is allowed. Anything outside that is illegal.... supposedly..... 
