Siping Strides
22 OVERDRIVE DECEMBER 2009 M odern tread designs are complicated affairs. Ribs, intervals between tread blocks, and hairline slits called sipes are interconnected to deliver higher levels of performance. Computer modeling has enabled exhaustive virtual and demonstration-type testing where the tread's behavior can be watched through glass. In due course, major tire manufacturers have fi gured out how to use siping to improve wet traction, prevent irregular wear and even help tires run cooler. The evolution of siping suggests that when purchasing new tires or picking the tread pattern for a retread, you should ask the company how any model's sipe design works with the rest of the tread pattern and how it affects the tire's lifespan. If you do off-road or severe service work, ask if the siping is compatible, as some sipes can trap small stones and cause damage. You might also want to talk about rotating a tire from its original position and how its siping is likely to affect operation on another type of axle. And, if you do your own siping, be sure to ask about how the Siping strides Tire makers take tread to new levels through advanced siping, improving traction and longevity. BY JOHN BAXTER Michelin's Matrix Siping consists of zig-zag grooves. In the contact patch, the walls lock together, which eliminates unnec-essary movement that can result in treadwear. C ou rt es y of M ic he lin