PURPOSE: To simplify the manufacturing and assembling of component parts of an auxiliary wheel for a pneumatic tyre, by foming the auxiliary wheel such that annular members each composed of a plurality of separatable sector members are fastened together with their dividing lines in the normal directions being shifted from each other, circumferentially.

CONSTITUTION: An annular member 1 having dividing lines on the vertically and horizontally normal lines and being separatable into four section members 1a through 1d and an annular members 2 having dividing lines on the 45° normal lines and composed of sector members 2a through 2d are fastened together by means of washers 3, bolts and nuts 4 with every dividing line extending between each adjacent dividing lines, so that an auxiliary wheel is formed. With this arrangement, since the divided annular members 1, 2 are composed of the sector members 1a through 1d, 2a through 2d which are miniaturized and lightweight, the annular members are easily fitted into a tyre. Thereby the auxiliary wheel may be simply assembled and firmly combined.