The fastest recorded tennis serve is about 260km/h but smash is far easier to do and shoot with far higher velocity. I am trying to find the maximum speed tennis players are able to shoot the ball and I feel the shot is smash, not serving. Correct me please if I am wrong. So what is the fastest recorded tennis smash?
The speed of overhead smashes that are hit during tennis points are not recorded (or at least if they are recorded, those metrics are not kept or stored anywhere permanent). The speed of the serve is mostly a gimmick for the fans to observe and - to my knowledge - it's only matches on the show courts at the 4 majors where any kind of statistics around serve speed is recorded and the data is kept as part of match statistics.
If I had to guess, however, it would probably be Roddick against Federer at Wimbledon ;). See this clip: https://www.youtube.com/watch?v=Uaw_P5ZX4r8