the tires i have are on 15 inch wheels and i went to put them on and they wouldnt fit. the hubs are too big and are diff. lug pattern i think.
do 78s come stock with 15's?
the tire on now is a snow tire that says.

7.00 x 15lt
is that a 15 inch wheel?
i have 33x12.5x15's to put on

The tire you currently have is a 15 inch bias ply and the 33's should fit depending on how wide your wheel is. My 78 came stock with a 15 inch wheel.

From the sounds of it that 7.00x15lt is probably older than you are!!
The 15 " tire was the only size available for your Bronco from the factory, but it sounds like you may have a wheel from a different vehicl, the bolt pattern you need is 5 on 5.5 ( 5 bolts with a 5.5" pattern)

i am just going to take the wheels it has on right now and put 33s on those wheels instead. i think they are just an old 15 x 7 or 8