Do I need to leave space in the room for expansion of tiles in different weather, or can I truly install wall to wall. Thanks.

When installing our 15mm Impact Tiles - Designer Series, we recommend placing a 1/2" expansion gap around your flooring to allow your floor to expand and contract throughout the day properly. This would still be considered a wall-to-wall install as expansion gaps are necessary for any floor to perform throughout the floor's life cycle properly.