I am about to change the tires on my cross to street instead of nobs. I'm running Hutchinson 30s on it now, but want something smoother for the street. Do they make a 30 street type or will I have to go down to a 28. What are the major differences? Will I get more flats with a 28 over a 30? I don't want to give up the smoother ride by going down too narrow. Comments appreciated.