Outer Limits 4x4 Board

I have read all the sticky threads and can not find the answer I need
Got a mate with a rocky with a 2 inch lift, with 15 inch rims, what size tyre can he comfortably out in them, looking for a all terrain . What brand does well on these little trucks and what should we pay for them.
Any help appreciated.
Would 30 x 9.5 x 15 be to big ???

30s on 7s will fit without any issues. 31s may rub just a little on your leaf springs at the front at full lock. Be aware, that fuel usage will increase with the larger tyres. Yes, even with 31s over 30s. I ran BFG ATs, in 30s, and had no dramas. When going out to play, I would change to my Simex Centipedes, in 31s on 8s. I adjusted my steering stops to suit, and just lived with the reduced turning circle. Not that the front locker didn't help with the reduced steering.