Definitely when vivibility is obscured. One morning I had never seen such rain and as I was ready to pull out of my road onto the main road, I never would have seen the car that went by had he not been driving with his flashers on.

That said, since I started riding and joining the forum last year, I've been wondering why red blinkies and not solid red with amber blinkies. Amber lights on vehicles is pretty much universally used for "caution."

As for people putting red on the front and white on the rear, really, you guys can't figure it out? This allows them to salmon without anyone noticing