Must be no problem. I've got also 265 at the front and 295 on the back, but both on 15" rims. I don't know the rules in the USA, but over here you must have the same wheels (size) at the same axle. If i will put 15" at the front and 18" at the back, it's no problem. But.... the tires have to be the same size left and right.
Edit; Be sure if they will fit on your wheelhub and check the offset. The must fit properly within your fenders. Only bad thing if you need a spare tire.... you have 2 different sizes.