Racing Slicks on the Road

The CWC etc. make vague noises prohibiting the use of racing slicks except on maintained track surfaces.  According to the rules, a slick takes a point of damage for every minute of travel off the track.  Given, however, that few of our battles last more than twenty seconds, it seems that this damage will never be a factor for racing slicks in-game.  It could be incorporated for realism into a scenario’s setup parameters (e.g., ‘Speedfreak has been driving for half an hour on the highway and his slicks have each already taken 3 hits of damage’), but banning their use outright off the race track seems unnecessary, especially when the double damage for spikes and road hazards is factored in.