How do you recommend laying down the rubber floor before the Nitro Tiles?

If you are going to use a rubber underlay under our Nitro Tiles, we would recommend loose laying the underlay under the tiles. You will want to make sure the subfloor is free of any major dirt or debris and free of any major pitting. If you wanted a more permanent hold on the rubber underlay, you could place some double-sided tape under the rolls.