At what speed do you want to attain 60 mpg? That's the $60,000 question.
If you're looking for 60+ mpg at 65+ mph, it's going to be quite difficult without extensive aero mods. I think I read you're planning to play with the fuel mapping via megasquirt (?) as well, which would also increase NOx emissions (assuming your goal is leaning fuel trim).
I can vouch for the rolling resistance performance of Bridgestone Potenza RE92 14 inch tires designed for the gen 1. Honda Insight:
http://ecomodder.com/forum/showthrea...eet-19126.html