My new truck ups and downs

I just bought my best friends truck he got from his grandfather all stock 91 single cab 4x4 He put in K&N, throttle body, flowmaster, timing chain, headers, CD MP3 player, very clean truck oh ya gun rack,

I tinted the windows ( no AC ) put some 6x9 behind the seats now for the down I just bought some MT rims with 30x11.5x15 sx super swampers (will the rub)???????broke 3 lug nuts because the center cap got stuck they came off a chevy, spent 90 bucks on lug nuts that would fit toyota the tires are much louder then my bf AT,



1: will those tires rub on a stock truck ( I dont want to lift)?

2: if I fill the tires Max will they quiet down , can I improve gas?

3: is a role on bed liner worth it for 200 or should I play 400 for a shop to do it?



sorry for the spelling I'm no pro.

wish I could post a pic but cant figure it out i have one on my desktop