I should probably file this one under, "No Duh," but I swapped out the stock Pirellis on my yellow R1T for some Toyo Open Country IIIs. Why? I was watching a friend drive my truck off-road and the sidewalls were deforming on really thorny rocks. I wanted something beefier.
The green R1T is the MotorTrend long term test vehicle (when it won Truck of the Year, Rivian gave us one for a year to review) on the stock Pirellis.
It wasn't the greatest comparison test in the world (we meant to go off-roading but Califronia rains had other ideas), but we charged both vehicles to 85% on the same charger, then drove 36 miles at the same speeds (between 35 and 75 mph) and the yellow truck burned 7 miles more (showed 7 miles less range) than the green truck. Pretty much as expected, but pretty disheartening all the same. I really like these Toyos (ride quality is much improved, plus off-road they're better).
Don't know if this means anything, but the green truck has about 20,000 miles on it, and I've put about 4,000 miles on these since I got them. The Toyos weigh 7 pounds more each.