Given that tires are round, you'd think it wouldn't matter which way they rolled down the road so long as they were pointed in the same general direction. That used to be the case, but some modern tires have 'unidirectional' tread patterns designed to force water from under the tire and out the sides.
Unidirectional tires are designed, marketed and sold as excellent wet weather tires. The Goodyear Aquatread was an early, heavily marketed example that sold well despite its lacklustre traction in the wet. (We don't care for what they do to a cars steering and refinement but that's a topic for another time).
A unidirectional tire mounted incorrectly collects water instead of cutting through it, hydroplaning far more quickly than a non-directional tire. If all four tires are mounted 'backwards', a driver may notice the lack of traction and slow down to the point where the car feels stable. Obviously the chances are slim that all four tires will end up facing the same way,which may lead the driver to think there is more traction than there really is as some tires are literally skating along on the brink of hydroplaning.
And even when mounted properly directional tires are noisier and tend to wander (as if the car has a bad alignment).
Given the safety risk, you'd think that this was a rare occurence, yet we come across examples a few times a week. We suggest you check your tires for an arrow, usually alongside the word "ROTATION." Alternately you can choose a tire that does nearly as well in the wet without the inherent side-effects of a unidirectional tire - contact us for more details.
