A forestry vehicle comprising:- a chassis (2)；- first and second pivot arms (3) arranged on opposite sides of the chassis (2)；- a drive wheel (5) rotatably mounted to each pivot arm (3)；- a rotatable idler wheel (9) carried by each pivot arm (3), the diameter (d) of the idler wheel being equal to or smaller than half the diameter (D) of the drive wheel； and- a track belt (12) arranged in an endless loop around each drive wheel (5) and the associated idler wheel (9).Each idler wheel (9) is located on that side of the drive wheel (5) that faces the pivot axis of the associated pivot arm (3).
