Outer Limits 4x4 Board

hi guys my brother is currently running a SWB 91 vit, we recently bought 15x5.5" sunraysias and want to fit some A/T 30 inch tyres with eventually a 2" body lift. We just wanted to know how wide can we go with the 30" tyres to fit the 5.5 rims?

Legally you can't fit wider than 215's but there are some who have put up to 9.5's on them. Why did you buy that size as they are the same size as standard?