Tesla Costa Mesa Service Center quoted me $1,680 plus tax ($1,814) last week to replace my staggered 21" Michelin Pilot Super Sport tires on my 2015 P85D's staggered Arachnid wheels.
I declined since America's Tire (a.k.a. Discount Tire in other states) quoted me $1,572 including tax... Plus they offer optional Tire Certificates (free replacement road hazard protection) for a few bucks per tire which have gotten me 2 of these expensive Michelin PSS tires replaced for free already. IMHO 21" tires are "fragile" if they "run flat" which happens FAST in a pothole blowout... or even a puncture.