^^^It's not just the sidewalls themselves (let's face it, NOTHING is going to stand up to the impacts/roughness/sidewall shearing of gravel roads like a totally reinforced, '3 ring' RALLY TIRE sidewall ), but the toughness, or durometer of the tread blocks themselves.
I could be wrong, but the R2's tread blocks, 'sipeyness', and the tire's exclusive intended use, make me think that they will get torn to shreds quickly on gravel roads, at summer ambient temps.
I could be wrong, but the R2's tread blocks, 'sipeyness', and the tire's exclusive intended use, make me think that they will get torn to shreds quickly on gravel roads, at summer ambient temps.