The traffic stop is for breaking some kind of traffic law, usually.
I suppose you could have a reasonable suspicion stop, but it would have to be something like "a hit and run just happened nearby, no vehicle description", and you witness a car with a smashed grill and leaking radiator fluid, but not breaking any traffic laws.
Reasonable suspicion might develop over the course of the stop, e.g. driver is super nervous, the back seat is full of overstuffed black duffel bags, there is a powerful chemical air freshener odor, and the vehicle has just crossed the Mexico border.
Wouldn't the suspicion -- the observed fact and presumed implication -- need to be recorded before the traffic stop?