Thanks, jerry, cdf, AR, Cyclone, et alia. Much appreciated.
I'd like to replace the OEMs in 3 months, before heading from LA to the Custer Rally (3rd Annual Sound of Silence 2016 Black Hills Tesla Rally in Custer, SD - everyone should make this journey at least once as it's history in the making, a great group of people, and includes some of the best barbecue on the continent).
By then, the tires will have between 40,000-45,000 miles thereon, and presumably I'll have made a decision by then about keeping the car past 50,000 miles (which, given the screwed-up ESA verbiage, the variable service experiences this past year and the frequency thereof, appears highly unlikely).
Fortunately, it appears that insofar as tires go at least, there are solid choices - and predictably, one appears to get what one pays for (either 45,000 miles with a top-shelf tire, or 24,000 with the next shelf down). Translated, about $650 twice or $1450 once. Every 18 months, at this rate. Hehe. I think I need to run out of places to which to drive, except that it's been so much fun.