you must be an american...
In canada at least, there is fair bit more required than suspicion for a search, it was actually recently upheld that "smell alone does not constitute reasonable grounds for a search" meaning that if a cop smells weed but sees none and your not acting stoned or anything your fine.
basically you can get stopped and charged for illegal tints, just like an illegal muffler or having to many front lights, its a simple violation. Does nothing to give grounds for a search