My father-inlaw has a old military jeep w/ 600x16 LTB tires on it, i wanna replace them with regular tires what size is this to a normal person like me or do you need those type of tires?

They should be about 28.5" tall and about 6-7" wide. The "best" match I can think of given that the rims are likely 5-6" wide would be a 215/85/16 tyre.