I have a 2009 KLX250SF I ride offroad often with street rubber on it. Unless is loose sand or mud have not had any problems. I am not saying is as good as dirt bike, but for quick trail rides works fine for me,.

 

Yeah the Supermoto racers don't seem to have much of a problem when racing through the mud on the road / race tires.

Of course its not going to be as good as a MX bike overall, but for regular trails and providing the mud is not wet, you should be good !

 

How about lacing up a 19" rim for the front? Doesn't the CR80 and other bikes like that have a 19" front tire? 19" is a common size for street tire too. Might be a good way to go half way in between.

 

I've been thinking about doing this. It should be well under $200 for the parts.

Then again, I don't have the bike until Wednesday. I may change my mind after riding it.