Avon Viper Xtreme
The gloves both our contenders were wearing for this test were the latest track-day tire in Avon's Viper range: the Avon Viper Xtreme. The Xtreme's tread pattern is more minimalistic than the rest of the Viper line, delivering more contact patch of the tire during extreme lean angles. The rear Xtreme utilizes a mono-ply casing construction rather than the standard two-ply, which makes for a lighter and more compliant tire. Avon's Advanced Variable Belt Density (A-VBD) construction for the rear tire encircles it with a jointless belt. Avon claims these closely wound fibers at the center of the tread provide maximum stability at higher lean angles. The company also claims this belt "optimizes the way in which the carcass and tread distort under load, leading to cooler operating temperatures and allowing the use of softer compounds." The front is a standard two-ply construction with belts.
During our morning sessions, scrubbing in the tires was bordering on scary. The extremely soft sidewalls would flex as though they were losing air. After triple-checking that the tires weren't leaking and that pressures were at the recommended settings, we learned to adapt to the odd flexing. Once they are up to temp the side grip is decent. Feel from the front tire is slightly vague and doesn't inspire confidence to push your limits. Getting the rear tire to spin on corner exits was a common occurrence, and by the end of the day both tires looked like they'd seen enough. We wouldn't recommend them for a competent rider on a fire-breathing literbike. The Avon Viper Xtremes are available in a 120/70 front and 180 or 190/55 series rear. For more information, visit www.avonmotorcycle.com.