Yes the online tool isn't correct.
Support for Rivian and this tire seem quite real time. Save yourself the consternation and just email or call TireRack.
TR are solid folks in my experience - it may be worth a call. Maybe there is something they can do to help. If you PM me I’m happy to give you the name of the sales guy who was helping me. He’s been great.
Ah - bummer. I actually had to have them hold the tires until we go up to Vermont in two weeks - as of yesterday they were able to have the tires in VT tomorrow (no good because we are picking up the car in NY tomorrow :))
The confirmation from their technicians RE TPMS was happening in real...
Ha.
Here is a quote from the email I got:
The MSW is 2535lbs per wheel.
The Radius is 2480lbs per wheel
I haven't yet seen a picture of the MSW Type 52 wheel; nor a price as it happens. The Radius in silver looks like it'll work; and if something goes wrong, TireRack is a solid outfit.
I've been back and forth with TireRack on this same wheel for a winter tire set. I've had very good experiences with their customer service over the years - very knowledgeable and super responsive with any issues.