Should these tiles be sealed with the rubber flooring sealer?

You don't have to seal our 8mm Sport-Lock Rubber Tiles, but you can if you so choose. Typically people will seal their flooring when they are using it in areas where liquids will fall on the floor on a consistent basis like doggy daycares, kitchens, spin rooms, and the like. This ensures that any liquids that do fall on the floor do start to get into the small pores that can be found in the floor.