Idaho Code § 63-3607A: Primary or primarily.

(1) With respect to the use of tangible personal property, "primary" or "primarily" means the predominant or greatest use of the property.

(2) In determining the primary use of tangible personal property, all uses of the property shall be aggregated into total taxable uses and total nontaxable uses pursuant to the provisions of this chapter. The primary use shall be the greater of the total taxable use or total nontaxable use.

(3) The use of tangible personal property shall be measured in terms of hours, miles, gallons or other measure commonly or customarily used to measure or determine use of the property.