The 18" plus size for your vehicle would be the 235/40R18 at 25.4" or the 245/40R18 at 25.7" diameter. The OE tire is 25.9" overall diameter and you want to stay as close to that number as possible. The ride will get stiffer as you go up in rim size because you are making the sidewall of the tire shorter but the difference between the 17" and 18" on this vehicle won"t be drastic. What you give up in ride you will gain in handling and performance so you have to ask yourself which one matters most to you. If you like the feel of the road and how the car holds the road when cornering then step up to the 18" tires and wheels.
〉 Answered on Sep 9th, 2013 by Julie Scroggins, Vice President, CFO at Waukegan Tire and Supply Company Inc.