(a) A speed in excess of the limits established by Subsection (b) or under another provision of this subchapter is prima facie evidence that the speed is not reasonable and prudent and that the speed is unlawful.
(b) Unless a special hazard exists that requires a slower speed for compliance with § 545.351(b), the following speeds are lawful:
(1) 30 miles per hour in an urban district on a street other than an alley and 15 miles per hour in an alley;
(2) except as provided by Subdivision (4), 70 miles per hour on a highway numbered by this state or the United States outside an urban district, including a farm-to-market or ranch-to-market road;
(3) except as provided by Subdivision (4), 60 miles per hour on a highway that is outside an urban district and not a highway numbered by this state or the United States;
(4) outside an urban district:
(A) 60 miles per hour if the vehicle is a school bus that has passed a commercial motor vehicle inspection under § 548.201 and is on a highway numbered by the United States or this state, including a farm-to-market road; or
(B) 50 miles per hour if the vehicle is a school bus that:
(i) has not passed a commercial motor vehicle inspection under § 548.201; or
(ii) is traveling on a highway not numbered by the United States or this state;
(5) on a beach, 15 miles per hour; or
(6) on a county road adjacent to a public beach, 15 miles per hour, if declared by the commissioners court of the county.

(c) The speed limits for a bus or other vehicle engaged in the business of transporting passengers for compensation or hire, for a commercial vehicle used as a highway post office vehicle for highway post office service in the transportation of United States mail, for a light truck, and for a school activity bus are the same as required for a passenger car at the same time and location.
(d) In this section:
(1) “Interstate highway” means a segment of the national system of interstate and defense highways that is:
(A) located in this state;
(B) officially designated by the Texas Transportation Commission; and
(C) approved under Title 23, United States Code.
(2) “Light truck” means a truck with a manufacturer’s rated carrying capacity of not more than 2,000 pounds, including a pick-up truck, panel delivery truck, and carry-all truck.
(3) “Urban district” means the territory adjacent to and including a highway, if the territory is improved with structures that are used for business, industry, or dwelling houses and are located at intervals of less than 100 feet for a distance of at least one-quarter mile on either side of the highway.
(e) An entity that establishes or alters a speed limit under this subchapter shall establish the same speed limit for daytime and nighttime.