Schwalbe Big Apple

The advantage of being a lot wider is you can run a lot lower pressure, so I ride these on the road at 35psi which takes up a lot more of the bumps an...

Or if you will be using it on actual mountain bike trails on the weekends then I would recommend something that can fit mountain bike tires. Sticking with trek the marlin is good for hybrid use because of cross country geometry and 29er wheel size, you can swap on some smooth tires like schwalbe big ben and it will be nearly as fast as the dual sport but really capable off road too.

With that rim size anything over 28mm wide will fit fine. Tire quality and tread pattern matter more than width or weight for casual riding. You might want to enjoy a fat smooth tire like a 60mm Schwalbe Big Ben that'll look right in the frame but roll well and quietly. That example isn't a light tire but it's sturdy and the rolling resistance is remarkably low.

Currently I have the Schwalbe Big Apple 24x2.0 on it. While riding, esp. with some load (\~10kg), I noticed that the sides of the tire are flexing a bit too much to my liking. I checked, it is not the frame (that too, but not so much), it is the tire that flexes, esp.

If you want some puncture protection and can fit a 48-50 wide tire, I would totally go for the 20 x 2.0" Schwalbe Big Apples with the racer skin sidewalls. I used them on the triplet for years. Relatively supple tire that never got a flat over 5 years of family riding. Primo Comets also come in a lot of sizes.