The purpose of this work is to develop a test method which will consider the variation of the ground clearance when driving, the so-called dynamic ground clearance. This has been done through the analysis of a specific application: the tractors in grain used in Brazil. Series of real life tests are run in order to obtain data on the tire compressions and the suspension travels. The tractor used is a 6x4 and is loaded with a trailer. When investigating critical cases, the minimum dynamic ground clearance is found to be as small as 123 mm at the axle 1, 78 mm at the exhaust outlet, 137 mm at the fuel tank, 35 mm at the bumper and 213 mm at the axle 2. These data will be transmitted to the engineer responsible for the chassis design in order for him to get a better understanding of the motion of the truck relative to ground.