tire question

[tractor12]

Have 16 and 18  wheels on pickups and want to know what size tire that  is tall and narrow that would fit standard rim . don't want to go wide, would like to have tall  with mud grip mainly . trucks do not have lift kits  , used on farm .chevy has 16  inch wheels and ford has 18 inch wheels.the ford is 2008 f250 . thanks for info.

[BA Deere]

That`s a question best answered by your tire dealer.

[Longcreekfarms]

235/85R16 is a good 10 ply tire. Or 7.50-16 if you want a bias ply mud tire that will last forever. I run them on my service truck and they are only 90 bucks a piece.
As far as 18", junk the things and put 16's on it. 18" has no room left in the sidewall to give over top of obstacles and so they get stuck everyplace. And cost is outrageous for them.