What inner tube should I buy for 47 tire size, 650bx47c tires?
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.