Fair enough. As I said, I dunno what the Civics come with, so I can't do the calcs to see how much off they'd be....I just know for the Accord. Even going 18" on the Accord with 225/40 or 215/40 won't change the speedo or odometer much.
I guess with the dinky wheel/tire combo on the Civic then it's not too hard to go up a ways in total diameter.
b