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One of the reasons radial racing slicks are so effective is because they feature shallow tread depths and their contact patch acts as a single unit. However, any tread design breaks up the contact patch into smaller elements and additional deep tread depth (required to enhance wet traction) allows tread block squirm which will reduce dry performance. This means that tires typically provide their worst wet traction ... and their best dry performance just before they wear out. However, its also important to remember that the heat generated every time a tire is driven activates bonding agents in the rubber. As this process is repeated continually throughout the tire's life, its rubber compounds gradually harden and loose flexibility reducing the tire's grip. Therefore, a shaved "new" tire will provide more traction than a tire worn to the exact same tread depth after being driven for thousands of miles on the road. Tire shaving is an effective means of permitting more of a tire's performance capability to be realized early in its life. Tire shaving removes tread rubber and reduces tire weight by several pounds. A shaved tire's tread profile will usually result in a slight increase in the width of the tire's contact patch putting a little more rubber on the road. The resulting shallower tread depths reduce the tire's slip angle, increases its responsiveness and help stabilize its cornering power by minimizing tread block squirm. Minimizing tread block squirm also reduces heat buildup and the risk of making the tire go "off" by overheating its tread compound. And in many cases, shaved tires used in competition actually have a longer useful life than tires that begin being run at full tread depth. So with all of these benefits, the next important question is: "How far should a tire be shaved?" Hoosier R3S03, A3S03, R3S04 and A3S04 radials are manufactured with 4/32 to 4.5/32" of molded tread depth and do not require tire shaving. Most other DOT-legal Competition tires begin with about 6/32" of molded tread depth. While some tires do not require shaving for dry autocross use, all of them will benefit from shaving to about 4/32" tread depths for driver's schools, track days and competitive track use in dry conditions.
NOTE: Depending on the severity of the track, vehicle performance and ambient temperature, Michelin Pilot Sport Cup and Yokohama A032R H tires can be track-driven without shaving. Most Ultra High Performance Summer tires begin with 10/32" of starting tread depth. Our experience is that shaving them to about 6/32" will provide a noticeable improvement and is a good starting point. However, it's also important to remember that once used, all tires will be much less effective during the next competition season. Therefore we recommend that tires be shaved to a depth that is sufficient to last for no more than one competition season. If it is very important to you to do well in the one event you run a year, a tire shaved to about 4/32" will further enhance your performance. |
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