Progressing from the streets to the Streets of Willow, we switched from the stock tires to two different varieties of aftermarket rubber. On day one we tried Bridgestone's new dual-compound BT016 Hypersport street/track-day tires. And on day two we sampled the Japanese firm's ultra-sticky, DOT-approved BT003 race tires.
The BT016s worked well during our group action photos and while doing preliminary chassis setup. Their quick warm-up and light, neutral handling allowed us to focus our attention on the bikes and get them dialed-in for the next day's flogging. Grip was surprisingly high for a street tire--only our faster testers piloting the GSX-R1000 and YZF-R1 had any traction issues. They're available in a wide range of sizes for most popular sportbikes with wheels from 16 to 18 inches in diameter at an MSRP of $147 to $247.
Replacing the previous-generation BT002s, the 003s are said to have a larger contact patch that offers more grip and better handling. Available in three single-compound varieties, Type 2 and 3 (hard and medium, respectively) front and rear tires feature a cross-belt carcass construction, while Type 4 (soft) tires have a more compliant, mono-spiral belt construction designed for low-grip and/or bumpy track surfaces.
On the recommendation of Bridgestone's tire ace Steve Turner, we ran a Type 4 front with a Type 3 rear. The combination proved to be a good choice, providing the right balance of grip, bump absorption and back-to-back session durability needed to explore our testbikes' limits. The added flexibility of the Type 4 front was an asset on the Street's seamed, patched and pockmarked surface, and helped reduce chatter in the decrepit skid-pad corner.
The 003s' round profile provides quick and consistent handling akin to the 016s, so the transition between tires was seamless. While the 016s tended to get greasy under the liter-bikes, the 003s never faltered, maintaining their grip despite the big bikes' massive power and 40-degree fluctuations in track temperature caused by the blazing sun and intermittent cloud cover.
Since the BT003s are race-oriented tires, sizes are limited to 120/70 front and 180/55 or 190/55 rear, which encompass the majority of modern sportbikes. Prices range from $189 to $288. For more information, check out www.motorcyclekarttires.com.