I have 20 red and 2 yellow retroreflectors. How should I use them?

I have a pack of retroreflectors. I notice that new cars in the US have reflective strips in their bumpers that are not part of the tail lights.

I also note that some cars have amber reflectors on the side quarter panel.

Should I apply the retroreflectors to the rear of the car? Is it actually going to make a difference in terms of safety? And should I apply the amber reflectors on the sides? Can you have too many red retroreflectors on the rear?

Ls400 said:

I have a pack of retroreflectors. I notice that new cars in the US have reflective strips in their bumpers that are not part of the tail lights.

Click to expand...

That's not necessarily or universally true. US regs require all vehicles made since 1/1/70 to have side-facing retroreflectors: amber ones as close as practicable to the front of the vehicle, and red ones as close as practicable to the rear of the vehicle. They're not necessarily "strips", they can be any shape. They may be integral to any of the car's lights, or they may be separate. They may be combined with the (also mandatory) amber front and red rear side marker lights, or they may be separate. What's required is that they meet the specifications for color, retroreflective performance, and angles of visibility. They are an effective safety device to reduce your chance of being T-boned, sideswiped, or hit while parked. Probably their biggest safety benefit is that if the car is electrically disabled and you wind up across the path of traffic, approaching vehicles still have a chance to see you and avoid hitting you. If you want to get the safety benefit, and your local laws allow it, apply them as described: amber as close as practicable to the front, red as close as practicable to the rear, facing straight sideways.