What is the wear resistance class of porcelain stoneware?

There are 2 main indexes of wear resistance of porcelain stoneware: resistance to abrasion (PEI) and resistance to deep abrasive wear. Therefore, first you need to clarify what kind of porcelain stoneware it is: In the case of glazed tiles you use the wear resistance class characteristic of the glaze (PEI) which has a value from 1 to 5. The least resistant class has PEI 1, the most resistant class has PEI 5. For the measurement of the abrasion resistance of the full-body or colored in mass gres you use the characteristic "Wear resistance of deep abrasive (ISO 10545-6)". It is measured in mm3 of abraded material, and should be less than 175 mm3. The lower the value, the more resistant the abrasive material is.