I vote genuine.
Aside from all the reasons so far posted, just think of the effect of aquaplaning on a car on a waterlogged road - depending on tyre condition, groove depth etc, aquaplaning can occur at 60mph. In other words, a wedge of water under each wheel is supporting a vehicle weight of circa 1500kg. Also, think of F1 cars on their slicks and how, at relatively low speeds they cannot generate enough downforce to break through the water and hence they skate off the track in all directions.