ORS 815.180
Standards
(1)
There are three different types of fenders and mudguards. Any vehicle required to have fenders and mudguards may be equipped with any fender, cover, flap or splash apron to comply with the requirements of ORS 815.185 (Operation without proper fenders or mudguards) for fenders and mudguards as long as the fenders and mudguards meet all of the following standards:(a)
The width of any fender or mudguard required under this section must be of sufficient size so that the fender or mudguard extends at least to each side of the width of the tire or combined width of the multiple tires when measured against the cross section of the tread of the wheel or the combined cross sections of the treads of the multiple wheels.(b)
Any fender or mudguard required under this section must be of sufficient size and must be so constructed as to be capable at all times of arresting and deflecting any dirt, mud, water or other substance that may be picked up and carried by the wheels.(2)
The following types of fenders or mudguards must cover the wheels of the vehicle in the manner described in paragraphs (a), (b) and (c) of this subsection:(a)
Type I fenders or mudguards must extend in full width from a point on the wheels that is above and forward of the center of the tires over to a point at the rear of the wheels that is not more than 10 inches, or, if attached to the rear of a dump box that elevates for unloading, not more than 13 inches, above the surface of the highway when the vehicle is empty.(b)
Type II fenders or mudguards must extend downward in full width from a point behind the wheels that is not lower than halfway between the center of the wheels and the top of the tires to a point at the rear of the wheels that is not more than 10 inches above the surface of the highway when the vehicle is empty.(c)
Type III fenders or mudguards must extend in full width from a point on the wheels that is above and forward of the center of the tire over a point at the rear of the wheel that is not more than 27 inches above the surface of the highway. [1983 c.338 §483; 1985 c.16 §252; 1993 c.314 §2; 2001 c.335 §9; 2003 c.158 §13]
Source:
Section 815.180 — Standards, https://www.oregonlegislature.gov/bills_laws/ors/ors815.html
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