I got a iron on kit. You can get any color, font, text, etc. Fairly cheap custom service. They aren't raised they look painted on. But they won't fly off at speed either or increase drag.
There are a lot of ways to go... From my research there are regular decals which last about 1-2k miles depending on weather. Then iron or heat on. They last longer, about 4-7k. The letter like the OP, which are raised glue on rubber letters. They are said to last the life of the tire but can be removed, but not without some cosmetic side wall damage.
I ordered stickers to try and see if I like the look, them if so I'll order the rubber glue on letters.