What's your concern with a wider tire? Is it handling, tire wear, or ??

I had good luck with 275/60/20s on factory 20's. They did wear a bit faster in the middle at 35psi. But they were great highway tires, ride was good, handling was good. Bonus - the cooper HT Plus in that size are both really great all around tires and super cheap. I used them as a highway set of tires that I used probably 85-90% of the time and kept a set of offroad tires on 17" wheels. At the end of the day - nothing was as nice to drive as the 265/70/17 touring tires that they come with. If you want a set for highway cruising - IMO that's the best option. But for the 20's, I was happy with the wider size.

The 255/60/20s look like a nice size. Just not sure I'd spend $1,200 for a set of those when you can pick up something comparable in a 275/60/20 for half the cost.

Good luck.