Directly from my contact at Toyo…
Carter,
We introduced a new race tire at SEMA called the Proxes R888. However, it will take time to expand the available sizes in this new product. As a result, the RA1 will not be phased out in 2007. We will continue to sell the RA1 in addition to the new R888. In fact, the RA1 may not be phased out until the end of the 2008 racing season. But it will eventually be replaced with the R888. All NASA race classes that currently spec. the RA1 will continue to do so at least through the end of 2007.
Please note that the R888 is simply a refinement of the RA1. It has a stiffer carcass construction, but utilizes the exact same tread compound as the RA1, so it will be just as durable and consistent. However, the new R888 starts at a shallower original tread depth of 6/32" instead of 8/32" like the RA1.