W = 500((LN/(N - 1)) + 12N + 36)
in which W equals gross weight, L equals wheelbase in feet, and N equals number of axles, except that two consecutive sets of tandem axles may carry a gross load of 34,000 pounds each if the overall distance between the first and last axles of the consecutive sets of tandem axles is 36 feet or more. The maximum gross weight allowed on a vehicle may not exceed the weight limits adopted by the department. The department shall adopt rules for weight limits based upon the most recent version of 23 CFR, part 658 , appendix c, for vehicles operating in Montana.
§ 61-10-107, MCA