Here you can find tubes for bicycles/ bikes.
Please use "improve your search".
You're looking for a tube for your tire, which is named 40-622. After ERTO (European Tyre and Rim expert organization), the tire has a width of 40mm and the inner diameter is 622mm. Search in this case just 622 ERTO. Inch sizes are sometimes confusing because for examble there excists 5 different 26 " inner diameters. Here is the most common internal dimensions 559mm (MTB). You can also select the type of valve, then the selection will reduce again. Explanation: e.g. 40/62-622/635 means: This tube is suitable for tires from 40mm to 62mm width and tire diameters from 622mm to 635mm.
Additional information can be found on the tube names here: Wikipedia or here: Schwalbe Technik (only German).