Announcing our new "CLUBS" section where you can join or create a Rivian club or group! You can use this new feature to conveniently plan and discuss local events, gatherings or other club/group related topics.
So we encourage you to join (or start) special-interest and regional-based Rivian clubs at: https://www.rivianforums.com/forum/group-categories/clubs-groups.1/
They have two different tire sizes now, so the real question is will it be easily configurable or possibly via OTA by request.I wonder if the Rivian electronics will accept inputs for different tire diameters to keep the speedometer in calibration and to make other adjustments to accommodate non-factory tire diameters.
Before I saw your picture I was thinking 275/65/18 like I have on my Toyota Tundra which I can get Toyo ATII for $225-250 a tire. When the tires jumps up in rim size they get more expensive. I think you are right about the calipers getting in the way with a 18" rim. Hopefully sometime down the line an aftermarket wheel company will make a compatible rimIn looking at pictures of the 20" wheel on the truck, there might not be enough clearance for an 18" wheel. I would have to take a closer look in person, but the brake calipers & rotors look pretty big, which is a good thing...