Just got a reply from Maxxis. They quit making the whitewall in 140/90-15 last April, even though it's still listed on their website, so the project I've been thinking about since 1986 comes to a close. I'll get my refund back from the dealer tomorrow. The lack of aftermarket support for this bike is amazing. Thought about lacing on a 16" or 17" hoop to allow more tire options but I'm not sure if I want to keep spending more money on it & then take 10 years to pay it off. Maybe the lesson in this for me is; ride more, tinker less.  

bummer about the whitewall,  there's got to be one out there somewhere.  

as for tinkering, my policy, never go to bed with things left to do.  

that is unless i'm doing something major, and thats not really tinkering.