[blucar]

Most states that have exemptions for "off road fuel tax" a red dye in the off road fuel.. In many states the fine is $150. per gallon of storage the tank can hold. ie; a 25 gal tank is 25 x $150. = $3,750.
I travel the western states on a regular basis driving many different sizes of vehicles, large diesel RV's, pickups pulling trailers and flatbed trucks.
In most states if the truck has dual rear wheels, more than two axles and has a flatbed and/or box, with a GVW in excess of 10K, in some cases the trigger is 16k, the vehicle is rated as commercial.
I know a lot of people that try to avoid the laws with vintage trucks that they claim are exempt from current DMV rules, however, when they get stopped by the law, they find themselves in deep trouble.