A PEI rating is given to a tile to show its resistance to abrasion. The rating is carried out in line with standards from the Porcelain Enamel Institute (PEI). Machines are used to mimic different levels of traffic and footfall. A tile is then given a rating from 1-5.
The PEI rating does not look at the thickness of the tile. By this we mean that just because a tile is thicker it does not mean it is harder wearing. So it is always worth looking at the REI rating for its surface durability.