Let's be clear: I don't necessarily think that the Michelin X-Ice Xi3 tires were forged of eldritch enchantments in the bowels of a fiery mountain. I'm pretty sure that the furry little things in Michelin's snow tire commercial are beavers rather than Hobbits. But there is a pride like fire among Michelin's Xi3 engineering team that makes one suspect that they're secretly thinking, “One Tire To Rule Them All...”
I first wrote about Michelin's excellent X-Ice Xi2 snow tire several months ago, and my only real issue was that the lateral grip was merely moderate rather than clearly superlative. Others had questioned its performance in deep snow. All seemed to agree that the overall handling was something special, and snow-tire geeks like myself have been eagerly waiting to see what the still-accelerating quantum leap going on in in siping technology would bring to Michelin's next generation.
Well I have Been Up To The Mountain – quite literally! Michelin kindly allowed me to join a number of other journalists for the launch of the X-Ice Xi3 at a track called Mecaglisse, near Notre-Dame-de-la-Merci in the Laurentian Mountains of Quebec, where I got to drive the tires - pretty hard - for about a day. So what I can say for certain about the tires boils down to this: The Xi3 is clearly a much better snow tire than the Xi2. Much better.
The Xi3's arrive packed with a carload of new technology, including a new self-locking siping pattern, more tread blocks, tread blocks at variable angles, and an interesting "caterpillar drive" feature in the central circumferential groove.
- 15% More Tread Blocks:
By making the blocks more compact, Michelin has increased their number. The engineers claim that more blocks mean more channels and grooves, making the tire more efficient at water and snow evacuation.
- Cross Z Sipes:
Michelin calls their siping pattern the Cross Z Sipe. (Cross Zed if you speaketh the Canadian.) The Cross Z sipes on the Xi3 are the latest in 3-dimensional self-locking technology. The sipes feature the now-familiar zig-zag biting edge pattern, but with an inner topology in which the points of the pattern are offset to one side or the other deep into the tread. This pattern allows the tread blocks to flex just enough to open the sipes and present the gripping edges to the surface, but locks the tread block together to prevent any more flex than intended. This prevents the kind of overflex in the tread block that stresses the block, leading to faster wear and the kind of "squishy" dry-road performance that everyone hates about snow tires.
The tread blocks also feature serrations on the leading and lateral edges. These are intended to bite the surface even as the tread block is flexing upwards and away, or when the block is flexing laterally.
- Micro Pump Sipes:
The now-proven technology involving tiny holes in the tread that vacuum the last tiny layer of water off road surfaces appears on the Xi3 as well, but only half as many as on the Xi2. Michelin's engineers explained to me that the tread blocks, being hot from friction, generated most of this layer of water themselves. Setting micro pumps only on the last part of the tread to contact the surface ensured that water was removed just at the point of the tread block's maximum flex and grip.
- Variable Angle Sipes:
The Xi3's tread blocks have siping set at three different angles to enhance lateral grip.
- Teardrop Siping:
Cutting a small teardrop shape into the end of each sipe eases the shear force at a high-stress point that can crack the sipe. This also allows the block to flex more easily.
- Caterpillar Drive:
The central channel on the Xi3's features a number of small raised blocks that are staggered to grip onto deep snow packing the channel in a kind of "caterpillar effect." Michelin's engineers expect that this will improve performance in deep snow.