I think it's almost a guarantee that the P3D- in inventory right now are unlocked LR AWD models. The speed with which they flooded the inventory after the price announcement suggests that's the most likely answer.
So as far as tires go, I think you're going to see the same 3 options (as far as I know, it's been two Michelin models and a Continental that have been delivered on the LR AWD vehicles, someone correct me if I'm wrong). I think their summer accessory package is a complete separate offering with summer specific tires.
I have to believe this is why Tesla is sticking with its annual guidance of delivering at least 360k cars. Even after a record quarter last quarter, I believe they will have to average over 100k for the next two quarters to hit that number. Just doing a few anecdotal checks that are in sync with this thread, it does seem by offering the "stealth" MP3, Tesla has spurred at least short term demand by flipping the software switch on existing inventory and driven in new buyers or induced current owners to upgrade earlier than they might have otherwise.
I am not into the specifics of some of the hardware as others, but after reading this it seems as if by doing this there is also a positive margin impact, albeit small, but after Tesla was hammered by Wall St for their automotive GM in the most recent quarter, if my assumptions are true, this "stealth strategy" makes a ton of sense.