VOL. 51 ISSUE 21 MAY 28, 2011 P77
BY PAUL CARRUTHERS
PHOTOGRAPHY BY KEVIN WING
M
ichelin went all out in showing a group of journal-
ists recently that there is more to their new Pilot
Road 4 tires than the adage that always accom-
panies a tire: Round and black.
The Pilot Road 4 is the fourth version of Michelin's
sport touring tire and this year's model gets an upgrade
designed to improve grip (both wet and dry), durability
and handling. And the key to all of that is the sipes. So
what is a sipe and why is it called a sipe? A sipe is noth-
ing more than a small channel cut into the tire to help
dissipate water from the tread's surface. It's called a sipe
because it was invented and patented in the early 1920s
by John F. Sipe when he cut grooves in the bottom of
his shoes to stop him from slipping. Depending on who
you choose to believe, Sipe either worked in a slaugh-
terhouse or was a deckhand. So he was either "siping"
blood from the bottom of his shoes or water. Michelin
uses them for water. And calls its use of siping, Michelin
XST (X-Sipe Technology).
The key to the sipes is compromise: You can have
too many and they can be in the wrong spots, and the
tire suffers because of it – especially if the grooves are
on the edge of the tire where you need the most rubber
for high lean angles. There have also been complaints
sipes can make the front tire feel squishy under hard
braking if the sipes aren't the right size and in just the
right location. Michelin counters this by putting fewer
grooves on the edge of the tire. The front tire also has
beveled sipes, which counters wear issues while also
improving feel under braking, according to Michelin.
As they say, the proof is in the pudding and Michelin
claims huge performance gains over its competition:
a 17 percent shorter (which equates to 15 yards) stop-
ping distance in wet-weather braking; and a 24 percent
gain on painted lines. Michelin also claims that the Pilot
Road 4 lasts 20 percent longer than its rivals.
The Pilot Road 4 comes in three versions (Standard,
GT and Trail) and all feature the same tread pattern. The
carcass on the Road 4 is more triangulated than on the
Road 3, which Michelin says is to provide a quicker
steering response. The GT version, however, gets a dif-
Michelin's sport-
touring radial tire
range has gone
from four models in
2013 to just the all-
purpose Pilot Road
4 for 2014.
