Just got a new to me 2014 F56 friday afternoon. Hit a pothole saturday night on the freeway, and busted the sidewall on the drivers rear tire. Was gonna replace them soon, just wasnt looking to do it in such a dramatic fashion as to have to drive down I-5 at midnight doing 35 with my hazards on for 40 miles. At any rate the question I have is about tires that will fit my 18 inch wheels and not rub or cause problems. I want a little more meat on them. The current size is 205/40-R18. I'm looking at 245/40-R18's. Has anyone got a little more experience with this?
205/40-18 245/40-18 Difference
Size comparison
Diameter inches (mm) 24.46 (621.2) 25.72 (653.2) 1.26 (32) 5.2%
Width inches (mm) 8.07 (205) 9.65 (245) 1.57 (40) 19.5%
Circum. inches (mm) 76.83 (1951.56) 80.79 (2052.09) 3.96 (100.53) 5.2%
Sidewall Height inches (mm) 3.23 (82) 3.86 (98) 0.63 (16) 19.5%
Revolutions per mile (km) 824.65 (512.41) 784.25 (487.31) -40.4 (-25.1) -4.9%

 

I have sumitomo 215/40 x zr18 on my Neuspeed 7.5x18s but I also have spacers . I like em . it's all about center of gravity & weight distribution. you wanna corner ? get low when I go by those speedo measurers on the side of the road my speedo is on the money

 

That extra inch of diameter is going to throw off your speedometer, mileage, and possibly cause major rubbing and clearance issues.

My suggestion: get rid of the 18’s and get a set of 17 inch rims and 215/45-17 tires. The extra sidewalk will help with ride quality, and hopefully keep you from destroying tires from potholes.