Freaking steal of a deal for those wheels (as in, someone might have lifted them...) Hopefully you won't have any excessive backspacing issues to deal with, or you may end up needing some bolt-on spacers. At least you're already the right bolt pattern so they won't be too expensive if you do end up needing them - check ezaccessory.com for a decent deal on quality spacers.
Tire size, beats me, I usually run more drop.
But I'd say you could probably get away easily with something like a 275/45/20 which is a very common size, sits right at 30" tall and roughly 8.5"~9" wide, if I recall it's the OEM size on the original Ford Harley editions and maybe some others, and it's available in the higher load ratings making it suitable for use on a truck. It's a beefy fit though, here's a set of them on my old Suburban which was running a 2/2 (rear is already lower on a Sub as they sit basically level, so it's comparable to a 2/4 on a truck)
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Or if that's just too much tire, go to tire rack's site and look that one up then pick any popular brand/model tire and click "specs" to look down the list for ones that are shorter in height.
Richard