Per this article, all Toyo bucks are now good to 3/31/13 to allow time for the RR transition:
www.nasaproracing.com/2012/10/nasa-specs...proxes-rr-by-to.html
To assist competitors with the transition period, Toyo is making a significant concession and allowing any Toyo Bucks issued from this point forward to be used toward the purchase of the new Proxes RR tire along with extending the expiration date on all Toyo Bucks until March 31st, 2013. This should allow competitors collecting Toyo Bucks from now until the end of the year the opportunity to spend their Toyo Bucks on the new RR tires for next season.