I think you'l be fine. We have some bad roads in MI and I've been driving daily on 19's for 3 years on my 340i with no issues. I have 20's on my Boxster, again no issues. I never purchase the tire/wheel insurance on my cars/bikes and have been fortunate so far. Although I do hear that some folks just "happen" to get flats/damage right around the time the tires are worn, coincidental timing I'm sure.
