Hmmm...odd my 2021 Warlock is riding on 275 x 60 R20...So if I read you correct a softer ride is made by a bigger sidewall. I think I am already there I guess..
Yes, a bigger tire sidewall, not more rim.
Theoretically, more rubber will provide more cushioning effect, of course, terrain, # of plys, and load rating will also contribute.
You can play with the online calculators and find all the dimensional details. Below, I've used your tire size and the closest 17" tire to show the differences.
If you were using the same model of tire in both of these applications (# of plys/load rating), the 17" would likely provide a more gentle ride because of the additional 1.6" of sidewall.
Or, if you prefer the 285/70R17 with 1.4" increase on the sidewall.
https://tiresizecompare.com/?t=275-60r20-vs-275-75r17-in-inches
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