OK I gots some 17x7.5 and 17x9 volks coming in. I know everyone runs a a smaller series tire in the rear example for 18inch rims 35's in rear and 40's up front. I know its the right way, but why exactly. When I had my 18 volks I had 225/40 front and 245/40 rear and had no problems at all. With my new wheels I know everyone would run 225/45 fronts and 255/40 rears. Would it be so bad that I just run 225/45 front and 255/45 rear to. I just want to know what the cons are running the same series tires. thanks

 

The series changes to keep the tire outside diameter the same as stock - too big could rub fenders and lift car, too small leaves big fender gaps and lowers car. Besides looks, the tires all need to be close in diameter for the ABS to work properly. 225/45 and 255/40 are widely available and both 25" diameter. 255/45 would be 26" diameter = big difference.

 

Yeah 225/45 and 255/45 are widley availbe to for tires. But that makes no sense how a 45 series tires for front and 40 for rear is the same diameter of 25". The 40 series would be smaller then the 45. SO how are they both 25"?

 

The "40" and "45" relate to the percentage of the "255" and "225" repectively to give the right side wall hieght

 

exactly----

45% of 225 = 101.25
40% of 255 = 102

So the sidewalls are the same size.