Awesome, I new techinically they would work, and glad to see plenty of clearance. As I mentioned, there is a window within tire size standards, and some can be on the narrow end, or wide end for the section width (which you described as flat or belly for the sidewall profile) and also the tread arc width, which there is no standard for, and can vary depending on the tire design. The Goodyear Asym 3 is a narrower design, so probably not much wider in section width than the OE 255, so its a squarer looking tire on our relatively "narrow for this size" wheel. But the tread arc width is wider than the Ecopias since its a 275, so its a win!
Thanks for the feedback and pics.
yes, the tire will "relax" and break in, about 100 - 500 miles, as will mold release wear away from the tread surface if any was present, so handling will only improve. Thats the benefit of a UHP tire vs the low RR tire like the Ecopias. If you have only summer climate, then you are set!