Bob Neff kindly replied back to my question about 140 TW tires for 2016. He said he thought it was very unlikely that the 140 TW tires would be allowed for 2016. The Region Solo Board had elected to retain legality for the 140 TW tires for 2015 to allow competitors to use up their existing stock, and that it seemed by the end of the season that most people had done so, and were running 200 TW tires. He recommended buying 200 TW tires.
I gather from his response that the Region Solo Board may not have taken up the question yet for the 2016, but he seemed to feel pretty sure which way it will go. He also copied Jen Maxcy, who is the chair of the Solo group, on his reply to me. I'll let y'all know if I find out anything else.
Base on this, I'm going to pass over the Federal 595 RS-R and buy something in the 200 TW category.