The biggest size rim I'd put on a Civic would be 17", they are not designed to fit anything much bigger than stock without sacrificing ride quality. 18",19" and 20" rims will mess up your suspension, braking, odometer/ speedometer, and overall ride quality. I have 18" rims on my Accord, I can definitely tell the difference with ride quality from bigger rims. If you get some 17" rims and maybe lower you car, it should look really nice!!