I park my car on mine, as you can probably see with the four mucky tyre marks. No compression or cleaning issues though…
What are they like wet? Like spilt water or fluid. Being flat I expect them to be slippier than the chequered type. Are they slippy?
I've never taken a shower in the garage @bradders so i'm not sure!!!! I use my garage as a gym so i keep the tiles nice and dry. The chequered or dotted type are OK but bad for holding dirt and kneeling on.