if you like the tires and want them then get them and tell you boss to shut the F up, unless he wants to pay for the tires, or they are going on his truck... its your truck, your money, and your tires so to me that means your choice. i once had a boss like that and he was the biggest d!ck, i did some work for him a couple of years ago on the side for a couple weeks and that was the first time my wife ever met him, after i was done working that job, she asked me to never work for him again cause she thought he was the most arrogant bas**** and self infatuated d!ck... she said she didnt care if we lived in a tent shed rather i not work for a jerk like him lol...
so screw what your boss says he obviously doesn't know what hes talking about...
ps i dont care for the BFG AT tires myself but a lot of guys run them and like them, they are not a bad tire and i do think they look good on a 4runner!