Why battery size changes the math
A large-pack truck takes considerably longer to replenish than a compact sedan. At 48 amps a Rivian gains roughly 25 miles of range per hour; at 32 amps it is closer to 16. Over a full overnight charge both work for typical driving, but the higher amperage is noticeably more forgiving.
Panel requirements
A 48-amp charger needs a 60-amp dedicated circuit and meaningful available capacity. On a 100 or 150-amp service that usually requires a load calculation and sometimes load management.
This is the most common reason a Rivian installation quote comes back higher than expected, and the most common thing a panel photo resolves up front.
Garage and driveway considerations
R1T owners frequently park in a driveway or a deeper bay, which can push the charger location farther from the panel. Cable length and mounting position are worth deciding before the estimate.