Will 33 12.5 15s fit on stock 15x6 ford rims. I would be mudding with them and driving on the street alot too.

 

They might it probably would be up to whoever was mounting them, you really want a 8in wide rim for that wide of a tire, I have my drag tires setup on 15x6 ford rims and the guy had a hell of a time mounting them, but the sidewall was alot smaller and they are not as wide.

Your tires will not be riding right and will wear wrong, if it was just for mudding I think if they mounted them then go for it but you said alot of street driving so i would try and find a more suitable rim,

 

Tryin' to stuff that wide of a tire on that narrrow of a rim is just plain silly. And dangerous.
Find something wider.

 

I was running 15's on my 2wd and had nothing but problems. There is a reason these trucks came with 16's, the calipers and tie rod ends were rubbing the inside of the rim. I know your truck is 4x4 and the wheels your talking about are alot narrower than mine were so it may not be a prob for your but you may want to look into it.

 

Can you do it? Yes. Is it a good thing to do? No

 

I run 15x8's on my 96, they fit fine. I think it is when the went to the dual piston calipers is where people have problems. I am not sure of the years of the transition though.

 

00 and 01 have dual piston calipers and 15's take work to fit, the guy at the tire place said 94-99 can take 15's but on a 15x6, i wouldnt do it, get a 15x8 or get 16x8 with 305/70R16's that what i have

 

The issue here is not the 15" rim, the OP isn't even asking if they will fit on his truck. He is asking wether a 12.5" wide tire will fit on a 6" rim. Honestly I doubt it, I used to work in a tire shop and that would be a PITA to mount if it even went on. Get 8" rims at least for that wide of a tire.

 

Exactly, I had 15s on my '98 with no problems, BUT 15x9s for my 35x12.5 tires. You will have nothing but problems trying to run a 12.5" tire on a 6" wheel, I ain't even sure you'd be able to find a place willing to try to mount them, the bead won't seal for sh*t.
Rule of thumb is a wheel should ideally be 3-4" narrower than the tire, although a half inch or so either way would be ok.

 

Most tire shops WON'T mount those tires, and a 6" rim. That is dangerous. You really need at least an 8" rim for those.......