Do these tiles get hot in the sun? We're looking for something to put over a concrete slab that will be cool enough to go barefoot...San Diego...

The tiles when in direct sunlight will get warm under foot. Black will be the hottest color by far. To keep the tiles cool, you can run a hose over the flooring surface. Rubber is more slip resistant when wet, so the floor will not present a slip hazard for anyone at play.