Motorcycle reflective wheel tape.
1. Comes in variety of colors to match your smart (including black).
2.Takes 15 minutes to apply. Last years.
3. Easy to remove.
4. Helps dramatically increase car visibility at night at the intersections.
5. Cost around $15 for all four wheels.
I bought it long time ago, but waited for new wheels to install it. I used KEITI wheel tape. It comes with installation tool, but it is piece of crap. At least I was not able to use it on my wheel properly. I applied by hand without any problems. I bought it from e-bay, but you can get it from most motorcycles stores online.
You can find big variety on ebay if search for "reflective wheel tape" or "reflective wheel stripe". Also many online stores cary them
They come in short 1 ft stripes or one roll. I prefer the roll, because it looks cleaner.
During the day you cannot see it at all unless you are two feet away and looking directly at it.
Here is some photos:
Here is the shot without the flash during the daytime.
With a flash.