This 90/100-14 (3.00-14) inch inner tube (innertube) is commonly (though not exclusively) associated with 90cc, 110cc, 125cc, 140cc, 150cc dirt bikes and pit bikes. Most commonly used for 1.85x14 rear rim in a 14 inch rear / 17 inch front configuration.
 
Commonly associated denotations:
3.00-14
90/100-14