29+ Tyre is limited to a 29×3 Knard at the moment I believe with a more knobbly 29×2.75 Dirt Wizard coming later this year.
Standard rim choice is a 50mm Rabbit Hole, but I think the Knard can go on a 35mm wide rim at a push so that gives you a Velocity P35 at 35mm or a newer Dually which is 45mm. Although I think Syntace do 35 and 40mm wide rims as well.