The main tractor parameters that defy suitability of tractors to perform traction work is traction power and driven axle wheel-slide. Different mass tractors wheel-slide on the same soil differs and depends on the vertical load (G), which falls on the driven axle wheels. When choosing tractors and agriculture implements it is needed to foresee the formed implements traction and economical parameters. To achieve this goal mathematical modeling methods are used. The purpose of mathematical modeling is to
determine traction characteristics of the tractor, taking into account various factors. At this moment there are tractor traction models created, that describe various agriculture and field tasks. Most Mathematical models mainly assess the hardness of the soil and driven wheel geometrical parameters. However, one of the most important parameters in assessing the suitability of a tractor unit is the tractors driven wheels slide. To decrease wheel-slide and to increase the driving wheels grip with soil there are different methods being used: Ballast weights, use of twin wheels and changeable air pressure in the tires. However current mathematical models do not consider the change of air pressure in tires. A mathematical module was created, which takes into calculations the driven wheels wheel-slide having different air pressure in the tires.