Trying to buy tires for my truck, what can I get for as cheap as possible?

I have a 1976 Ford F150 and the tires that are on it right now are 33 inch tall by 12 inch wide with a 15 inch rim. Which translates to a 305/75/15, these are definitely expensive and I can't find any on any tire site. It just says they aren't available. Where can I find some tires, where should I get them from and how much are they going to cost.

How much horsepower will be added?

I have a 2006 ford f150 harley davidson edition and a supercharger was put in it from previous owner, about how much horsepower and torque should it have with the supercharger?

1999 ford f150 v6 rough idle and spark plug questipn?

My 99 Ford f150 is a v6 and I'm having a rough idea or a miss while my foots on the brake and its in gear it idles like it wants to die. I just noticed the 3 plug wired on the passenger side were burnt so I imagine its spark knocking. But my question is what plugs should I use and is this my only problem causing the rough idle? But should I go with e3s?

Why does my truck do this?

I have a ford f150 xlt 2004 v8 5.4l and i've noticed that when I take my foot off the break it accelerates but like if id be stepping on the gas. I know that by taking my foot off the break itll mve but what i'm trying say is that. Like when you have it on park and you step on the gas well it does that but when I put on drive it tends to go on its own. Why does it do that

Have a rattle in passenger doors on 2012 ford f150 supercrew?

My passenger side has been rattling for the past few months last week I replaced the factory speakers with aftermarket and now the rattle is even louder which does not make sense because I zip tied all the cables and did all that correctly I don't know what it could be any ideas?