The floor materials use a Multi / Sub object material to randomly assign 20 plank textures. Unfortunately to change the tint you'll have to add a Colour Correct map for each diffuse bitmap. You may find the Modifier Modifier Zorb
script useful for making mass adjustments. Alternatively you could set up a batch process in photoshop and adjust or even replace the bitmaps themselves if you need something completely different, be careful though this would permanently affect all the floor textures and styles.
I hope that helps,