My 31 inch tires are getting pretty worn and I am looking at getting new tires in the spring. I have a 1999 4 cylinder and have no problem with power with the tires I have. Will there really be that big of difference going from 31's to 33's? I was thinking if there was I may go to a 32 inch tire. I have a 4 inch lift and the tires that are on it look just a little small for it, but I don't want a huge change in mileage and power on the highway as this is my daily driver.