I decided that im ganna get 33 x 12.5 x 15 tires. Im just not sure if i should 15 x 10 rims or 15 x 8. Which would be better or worse.

 

you should get 15 x 10.. Rule of thumb is to keep within 4 inches of tire width to section width.. It is possible to get the 12.5 inch tire on the 8 inch rim, however I believe the tire shop would recommend you going to a wider rim...