In the State of Idaho, it is legal to ride an ATV on the road in most towns. All you have to do is get street licensed (plates), install a mirror, use hand signals and check local laws. I found it a lot safer to install two mirrors, especially when traveling on five-lane roads.
The mirrors sold through the ATV dealers are worthless, unless you thrive on twisting your neck in five positions to get an accurate view. I prefer to take one look and see everything. So the mirrors of choice are truck mirrors, eight inches wide and ten inches tall. Large enough to stick a blind-spot mirror in the corner without robbing the view.
These mirrors are K-Source brand, model 3571. They cost about sixteen bucks apiece and come with a lot of hardware that you're just gonna turn around and sell at a garage sale for a buck and a quarter. You will notice the mirror will have a ninety-degree arm attached with a bolt on the bottom. Take the bolt out, buy one that is an inch longer. It won't do any good to tell you the size, because you are not likely to purchase the same make and model. Besides, I don't remember.
The brace arms and any other hardware you find in the box, take it out and sell it at the garage sale, like I said before. If you think you'll need it someday or might think of a use for it, put it on a shelf in your garage. Ten years from now, take it down, off the shelf and sell it at a garage sale. If inflation is in your favor, by then, you might get two bucks.
Look on your garage shelf, or in a box of stuff and find a bicycle seat clamp. That's what I did - I set them on the shelf ten years ago. If you didn't have the foresight to save the darn things, go to your nearest bicycle shop and buy one. Buy two if you're setting up two mirrors.
Place the seat clamp in a vice and drill the three-eighth inch square hole out to a half inch round hole. A half inch square hole will work as well if you have the proper drill bit for it. Make sure you have it securely seated in the vice. I use one of those big, iron bench vices. If the drill bit "bites," you will rip the clamp out of the vice and twist it up pretty bad. I learned that one the hard way -- and it hurt, too!
Next, take the clamp, open it up, and wrap it around the outside leg of the front cargo rack. Use a pair of wide-mouth adjustable pliers to snug the clamp around the metal tubing. If you are not sure what tool that is, some call it tongue-and-groove pliers and others call them Channel Loc, but that is the original brand name. Like saying Kleenex for facial tissue, or Formica for plastic laminate counter top material.
Now all you need to do is put the bolt through the two holes in the clamp, making sure to use the washers that came with the mirror, and through the bottom end of the ninety-degree arm holding the mirror. Snug the bolt tight but not too tight. Adjust your mirrors and you are ready to go.
Don't forget to install the small, round blind-spot mirrors in the lower, outside corner. These are really helpful so you don't have to move your head in five positions to see everything and so you don't have to turn your head. I always wear a helmet and a helmet is good at blocking a good portion of your peripheral vision when your head is turned. The blind-spot mirror will eliminate that problem.
Here is the finished product. These mirrors trim the ATV out very nicely and they are sturdy enough to hold up off-road; even in the woods. Even off-road, the mirrors come in handy because they make it much easier to see everyone behind you.
You might notice the helmet in the back. I believe in safety and that helmet is a full-wrap to give my face and head all the protection possible if something should go wrong. I have experienced great pain and I will do everything possible to avoid it. Another benefit of a full helmet, especially one with flamboyant colors, like this one, is that other drivers can see you much easier than they can your plain, bald head. Safety is important -- it will keep you on the road, or the off-road, a lot longer.