Alright guys, I don't want to sound stupid but here it goes. I have an XR 650 R that is plated for California. I use it to commute to work on back streets along with weekend rides in the desert. I was hoping for some advice that would get me to comfortable riding speeds on the freeways for short periods of time. I currently have stock gearing. To the best I can calculate I should be running a 15/42 sprocket combo to get me there. I don't know if I have calculated right but I don't want to tear the thing up. It would only be for short runs and I am willing to set up a second set of wheels in order to have a set for running around on the streets/freeway and for when I go to the desert. Any help would be great.