Utah Code Ann. § 41-6a-1633
(1)
(a) Except as provided in Subsection (2), when operated on a highway, the following vehicles shall be equipped with wheel covers, mudguards, flaps, or splash aprons behind the rearmost wheels to prevent, as far as practicable, the wheels from throwing dirt, water, or other materials on other vehicles:
(i) a vehicle that has been altered:
(b) The wheel covers, mudguards, flaps, or splash aprons shall:
(2) Wheel covers, mudguards, flaps, or splash aprons are not required:
(b) on a vehicle operated or driven during fair weather on well-maintained, hard-surfaced roads if the motor vehicle: