I will be putting. 20x8.5 wheels with either 225/35/20 or 235/35/20. The 245 are recommended and even guaranteed from some folks but I've even been told that it sticks past the fenders. I personally don't want this look.
Your offset should be between 35+ to 45+.
Oh by the way, if you stick with the 225 or 235 sizes, you will not need mods done.
245 and up, possibly and likely, shaving will need to be done to avoid the rubbing.
I have been shopping, researching, measuring, calling, getting quotes, even contacting some manufacturers Tech Support department from the West coast to the East coast and I have heard MANY opinions on what would fit and what would not. I just took plenty of notes and made my own decision off of what I learned.
This goes as well for me, this is my opinion with my own personal research so when I get my 20's, I will give you more info. Please share as well if you get yours before me.