Hi, At the moment I'm using 40-120 DR Lo-riders on my 5-string. I'm looking for ways to get a smooth tone and was wondering what kind of strings I should try (obviously the basic sound of my bass plays a role). I was thinking about nickel-plated heavy-gauge strings. I'm not sure if I'd be ok with the "flapping" sound of flats, although I've never played those. So, any suggestions?
Try some half-round, groundwound, pressurewound, etc. They're in between rounds and flats, soundwise.