There is a large amount of so called rework in the tire manufacturing industry, especially when starting and finishing the manufacturing process. The great number of variants that are produced due to smaller batch sizes result in a permanent increase of the amount of rework. It is not waste that we are dealing with here, these intermediate products are of high quality that can be reworked equivalently. This article is about an expert system that supports the rework of unvulcanised rework in the tire manufacturing industry. It calculates the percentage of the rework for every possible combination of recyclable materials. Furthermore it calculates the new recipes and gives hints concerning the workability of the mixtures to be produced. The acquisition and representation of knowledge takes place on the basis of the expert methods and way of thinking. The system plays an important role in the Total Quality Management of the company and supports an optimal rework of raw materials. The system development is completed and is successfully in use.