that's a really low average speed given the D+. If you put Conti GP5000 tyres instead of these Kenda, you will probably go a lot faster for the same effort. Either tubeless, or run with aliexpress TPU tubes. The bike will also feel much nicer to ride. Pretty much guaranteed. Upgrading from poor tyres may be the best upgrade one can do on a bike. In Europe the non tubeless version costs around 45 eur per tyre, and they're made in germany.