my '09 is set up with street tires. I thought about getting another set of rims with dirt knobbies. The idea is to swap the two when ever i ride more dirt. Like next week i want to go ride some logging roads. I know my street tires should be ok, but the few times ive had them off road i didnt lke how they performed. So is swapping back and forth a bd idea, especially on the chain and sprockets?