2011 ORS § 811.105¹
Speeds that are evidence of basic rule violation

(1) Any speed in excess of a designated speed posted by authority granted under ORS 810.180 (Designation of maximum speeds) is prima facie evidence of violation of the basic speed rule under ORS 811.100 (Violation of basic speed rule).

(2) If no designated speed is posted by authority granted under ORS 810.180 (Designation of maximum speeds), any speed in excess of one of the following speeds is prima facie evidence of violation of the basic speed rule:

(a) Fifteen miles per hour when driving on an alley or a narrow residential roadway.

(b) Twenty miles per hour in a business district.

(c) Twenty-five miles per hour in any public park.

(d) Twenty-five miles per hour on a highway in a residence district if:

(A) The residence district is not located within a city; and

(B) The highway is neither an arterial nor a collector highway.

(e) Fifty-five miles per hour in locations not otherwise described in this section. [1983 c.338 §564; 1985 c.16 §286; 1987 c.887 §10; 1989 c.592 §5; 1995 c.558 §3; 1997 c.404 §5; 1997 c.438 §3; 2003 c.397 §6; 2003 c.819 §6; 2007 c.367 §3]