PURPOSE: To make a proper weight ratio of each of axles by a method wherein three adjoining axles are provided, one of them is made to be a steering axle of one steering wheel, and arm ratio of three sets of beams is set to a specified condition.

CONSTITUTION: Double wheel tyres 10 and 11 are mounted on the axles 7 and 8 of the large-sized construction vehicle e.g. rear axles 7W9 as nonsteering axles, the axle 9 has a single wheel tyre 12 as the steering axle. At the lower part of a chassis 1 a pair of right and left balancing beams composed of three boggie beams 13W 15 of front, central and rear parts. Each of the beams 13 and 15 is pivotally supported at the lower surface of a chassis frame 2, the beam 14 is pivotally supported at the lower surface of the central axle 8 via brackets 16 and 18 at each of the intermediate portions thereof, one end of the beams 13 and 15 is pivotally supported on the beam 14. Then, an arm ratio of each of the beams 13W15 is set such that a rate of axle weight of each of the axles 7W9 is set in a range of 1:1:0.4W0.7.