Is it safe to merge into the right lane if a car is visible in your right side mirror?

Merging into the right lane while a car is visible in your right side mirror is generally considered unsafe because it suggests that there is another vehicle in proximity to your position. The presence of a visible car indicates that it could be in the lane you want to move into, potentially leading to a collision if you attempt to merge without ensuring that the lane is clear.

To merge safely, it is crucial to check for other vehicles in both your mirrors and your blind spots, ensuring that the lane is completely clear and that you have adequate space to maneuver without endangering yourself or others on the road. It's always essential to prioritize safety over the desire to change lanes, even if the visible car appears to be at a distance or moving slowly, as its speed and intent can change rapidly.