by Jad on Thu Jun 07, 2012 11:45 am
This is very common. Same is true with rims, like the Porsche Twist, they twist forward on one side, back on the other. I am pretty sure the major reason is cost savings, but the minor difference in groove direction is minor as long as you keep the BIG blocks of tread on the outside and the smaller on the inside, thus the OUTSIDE labeling. Too expensive to have 4 unique rims and tires, prevents any tire rotation, etc.
Some tires are unidirectional, but that trend seems to be going away, with the inside/outside taking over.
Just my findings, you could ask at the tech session....