(a) A motor vehicle, other than a truck-tractor, may not be longer than 45 feet.
(b) A motor bus as defined by Section 502.001 that is longer than 35 feet but not longer than 45 feet may be operated on a highway if the motor bus is equipped with air brakes and has either three or more axles or a minimum of four tires on the rear axle.
(c) The limitation prescribed by Subsection (a) does not apply to a house trailer or towable recreational vehicle or a combination of a house trailer or towable recreational vehicle and a motor vehicle. A house trailer or towable recreational vehicle and motor vehicle combination may not be longer than 65 feet.
(d) In this section, "house trailer" and "towable recreational vehicle" have the meanings assigned by Section 541.201.