What inner tube should I buy for 47 tire size, 650bx47c tires? I'm pretty new on this and want to buy a spare inner tube. These are my specifications of the tires:

Tire Size 47
Tires Maxxis DTR-1, 650b x 47c
Wheel Size 27.5
Presta valve

When I'm browsing, I see results like:

Inner Tube - 650B/27.5&quot; - 27.5&quot; / 1.5&quot; / 2.4&quot; / Presta
650x28-42 Bike Inner Tube - Presta
27.5&quot; x 1-1/2 (650x35) Presta Tube

But I have no idea what the 1.5&quot;/2.4&quot;, 1-1/2, etc. mean. Which one should I choose?
1.5&quot;/2.4&quot;, 1-1/2 are the tyre width ranges the tube is compatible with. Your tyre size is indicated in mm (ETRTO standard sizing), but 47 mm is 1.85&quot; so 1.5&quot; / 2.4&quot; is compatible.
The 650x28-42 is for narrower tyres. 1-1/2 (650x35) (1.5 inch, 35 mm)is likely too narrow as well, although one should check the actual lower and upper limits.