I have 245/60/r14 on standard 14X7 Rally rims, not sure of backspace measurement. They fit no problem, the speedo is off a few mph but not too bad. You need to find out the diameter of current size tires and compare to new size. I looked up standard G78/14 which compare to 225/70/14 that have a diameter of 26.50 inches. the 245s have a 25.60 diameter.
