winter tires

[Polonius]

From what I've read, the Blizzaks (being the first) are the only ones with the bubbles for only 50%. Because the bubbles made the whole tire too soft, so they could only be used for the outer half of the tread blocks. The rest overcame the problem in various ways. The iG20s, for example, coated the bubbles in carbon in order to maintain enough rigidity to use them throughout the entire tread. Other companies did various other things.