im getting some conflicting answers on this questions. i have a 1978 f-150 4x4 right now it is on stock suspension but i am planning on lifting it 4 inches can i clear 35x12.5 on a 15x8 ford rim or should i go with a 33 12.50.
it it more used in deep snow and mud than terrain crawling right now

 

Tires vary from manufacturer to manufacturer.

I am running 35x12.5s Goodyears on 15x8s with a four-inch lift with no issues.... except a lil doggy with 3.50 rear gears. Click on the link in my signature.

 

HIO silver "away"...you have one bada$$ F-bomb truck man!! It looks perfect!! Sorry for the hi-jack!!

I have 33's on my 79 F150 4x4 with 3inch lift. I put a set of 35's on it a few years back and it rubbed a touch at full lock, not bad tho...I just thought they didn't look right with 3inch lift so I went with 33's, but look at HIO silvers truck and they look awesome...here are a few pics with the 33's

 

While I have an F250, here's mine with a 4" lift and 35" BFGs. I think this combo is just about perfect for these trucks. Plenty of clearance lock to lock. With a 4" lift, you might need to finesse the steering geometry. My drop drag link needed more drop and the only drop pitman arms I could find dropped too much (designed for 6" I think).

 

another question with conflicting answeres whats the biggest tire I can run on stock suspension my lift has been back orderd ive heard I can run 33x 12.50 without a lift and ive found a set of bfg mud terrain 33x10.50 right in my price range can I run them without a lift

 

I believe that's true with 33x10.5 but not with 33x12.5s. Btw, my rig had a 2-inch lift with the 35s pictured when I bought it. In any case, wheel offset needs to be spot on.

Scott79s' rig is OH SO CLEAN.. in black nonetheless! I'd have to lead the caravan and break all the low hanging branches so he don't scratch his paint.

 

I ran 33x12.5 on 15x10 rims before I lifted my 79 f150. I will proabably get 35s next but currently 33s with 4" lift and lots of room. The passenger side rubbed the front of the fender while turning but it was because the fender had been out of alignment. If you do any wheeling to compress the suspension you will rub a bit. I think 33x10.50 would be fine with no lift probably better on fuel too.