That tire size should be the same as 31x10.5x15 so it should fit. I'm planning to get the same size when I lift 2", and people say it will rub on the control arms, and you have to trim a little from the fenders. Flareless might work too but I'm not sure.
For the beach I'd get BFG ATs... mainly because part of being on the beach is looking cool to get bikini babes, and no other AT really looks cool, except ones with higher void space (which would dig you into the sand)