Are my 33 BF Goodrich Mud Terrain Tires the cause of my bad Mpg's on my 1995 Ford f150?

My truck is a 1995 Ford f-150 Xl Sport. It's an In line 6 Cylinder 2wd with an automatic . Ford factory say my truck should get 14 city and 19 highway. Im getting about 10 in the city and that isn't with a lot of stop and go traffic. Ive changed the spark plugs, ran fuel injection cleaner, changed fuel filter, air filter, ect and it still get terrible mileage. I don't do a lot of drive at all either mostly to and from school and to my parents house. Could the Mud tires be the reason I'm only getting 10 mpg? Anyone help is much appreciated.