OK, you've got really two sizes available to do this. They will not throw off your speedo and allow all electronic functions to remain the same.
1) 20"x8.5" rim(+36-40 setback) with 275/45-20" tires
2) 22"x9.5" rim(same setback) with 285/35-22" tires.
Now, all you have to do is shop around for the wheel tire/combo that fits your needs. make sure you get a set of bands and Ford TPMS sensors so your dash won't be upset with you and keep saying "check tire pressure" I run the 20" size on my '08 with no contact issues whatsoever! Another member has the 22" setup and he has no issues. I will be switching to the 22" set because the salt air here has eaten up the chrome on the wheels. I hate messed up stuff. Good luck, Bob