If the dealership rotated your tires, then you need to take it back, get them to fix it and then find a new dealership and never ever go back to the one who rotated your tires!
Yes mistakes happen, but how on earth can you not notice when you are taking 245 off the front and 275 of the back?! If they can't even get that right then there's no hope for them.
In this case the below emoticon is unfortunately perfect...
