TASC (TYRES/TRACKS AND SOIL COMPACTION) is an Excel tool designed foremost as an aid in arable farming. The vulnerability of the soil to the passage of wheels or tracks is assessed after considering soil and load property factors. Danger of soil compaction is also apparent in the unworked underlayers. Factors included soil texture (finger test), penetration resistance in the pan layer (screwdriver test), depth of pan layer, size of tyres (width, overall diameter), load and inflation pressure. After examination of several field trials*, new algorithms will be developed and integrated into the model to obtain the contact area and the vertical stress propagation in the soil. For the assessment of the soil severe compaction risk, the concordance between the model data and field measurements is over 85 %. The tool is particularly well suited for traction tyres used on settled arable soil with a compacted plough pan between 20 and 25 cm depth. Technical data on more than 1’000 tyre types used in agriculture and forestry are available too. Information on tyre size can be directly imported into the program. According to ETRTO standards (European Tyre and Rim Technical Organisation), the tool gives the maximum load considering the tyre size, inflation pressure and speed of travel. TASC is developped firstly to protect prevently the soil from severe soil compaction damage with low reversible or irreversible character.