Now that we’ve talked about the rear view mirror, let’s talk briefly about the side mirrors. One reason to use your side mirror is to help you reverse into a parking space. Your side mirror can help you spot how close your vehicle is getting to that smaller parked next to you. Another reason can be seen from this photo. The cyclist approaching from the side is distracted with their cell phone. Checking the side mirror lets me know it’s not safe to pull out. If I don’t check and the cyclist is distracted, a crash could happen.
Checking the side mirror can be beneficial if a larger vehicle is directly behind you and completely fills your rear view mirror. The side mirrors can give you added views to what may be approaching from behind. For example, if you wanted to change lanes and a large transport truck was tailgating you, drifting slightly toward either side of your lane will allow you to see behind you through your side mirror.
Speaking of a large vehicle behind you, let’s say you’re stopped in traffic and a large vehicle is stopped behind you at your bumper. Since it may be difficult to see through that vehicle to know what’s approaching from behind them, you could be involved with the most commonly reported collision in North America – the rear crash.
Once you notice the larger vehicle is approaching from behind, you could begin to creep forward and drift to either side of your lane. Once you’re in that position, you’re now able to see through your side mirror to know if you need to get out of the way of a multiple vehicle collision. In order to be able to creep forward, you should leave extra space in front while stopped. More information of that technique can be foundhere.
Regardless of why you’re using your mirrors, make sure you are. I once had a licenced driver as a student who wasn’t checking their mirrors at all. When I brought it to their attention, they replied; “Why would I check my mirror? I’ve already been there”.
culled from http://safedriving.wordpress.com/