Aftermarket wheel help

[The.Most.Truth]

I need a bit of help. I am new to the whole aftermarket wheel thing. I just now only decided that I wanted to spice up my 2012 F-350 with a little shine. I have got the factory 20" rim with what I believe are the stock 275/65/R20/E. I am not totally confident in what I am reading when i see offset, backspacing and such. I want to keep the 20" rim size and the 275 tire size and keep the tires as tucked under the truck (stock) as possible and I don't want to add flares.

What numbers do I have to look at when considering an aftermarket rim? How do I know what width of rim to purchase? Any recommendations on wheels?

I want to put on the Goodyear Wrangler Duratrax in this size.

Any tips of info would be appreciated.

Thanks,
New Guy