Ok, I replaced all four tires. I know the front and back are different sizes. However, I had 4 like new 245x45 x18 and put them on my G35. Guess what-they are perfect and now I can rotate them every 5,000 miles!! I dont notice any difference in handling. I will stay with this size and not live with not rotating tires and buying new ones after 5000 miles!!!!