The info I posted was for LT265/70R17 E-rated. I don't see a listing for C-rated.
I'm not able to upload the PDF, but it's here:
https://www.toyotires.com/media/pxcj...s_20200723.pdf
Also, there's a good discussion of load ratings here:
Discount Tire | Tires and Wheels for Sale | Online & In-Person
I don't see a distinction between C-rated and E-rated for inflation recommendations; it seems that it's just a matter of the maximum inflated pressure, which then dictates the maximum load.
I note that when I plug a 2021 ORP into the Discount Tire site, it offers the C1- and E1-rated KO2s but not a C2. There may not be a KO2 C2 in that size, of course.
This all sounds to me like C-rated and E-rated should be inflated to the same pressure for the same load weight, and that we shouldn't be using C2-rated tires on 4Runners as there's no way to adequately inflate them.
Harshness: try riding on run-flats sometime. Stiff *and* noisy. E-rated Falken A/T3Ws at 40psi are almost silent by comparison.