This size inner tube crosses a variety of markets and applications and is therefore known by its application size as well as its inner tube size Size 4.00-6 also written as 400-6 or 4.00x6 or 400-6 Size 3.50-6 also written as 350-6 or 3.50x6 or 350x6 Size 3.50/4.00-6 also written as 350/400-6 or 3.50/4.00x6 or 350/400x6 Size 4.10-6 also written as 410-6 or 4.10x6 or 410x6 Size 13x5.00-6 also written as 13x500-6 or 13x5.00x6 or 13x5-6 or 13x5x6 Size 4.10/3.50-6 also written as 410/350-6 or 4.10/3.50x6 or 410/350x6 This will fit a wheel rim that has a diameter (distance across the middle of the wheel) of 6 inches (15.2cm) and a wheel width,distance from one side to the other of 13 inches (33cm) - PLEASE NOTE This innertube fits a number of different size tyres. Not all of the sizes this innertube fits will be printed on the innertube itself, as the space is limited. If the size you purchased is not written on the innertube or is written differently dont be alarmed, it will fit your tyre if your size is listed within the range of fitment sizes on the product listing. We market different innertube sizes to different product markets, the size is superimposed on the product images so buyers know it will fit their size tyre.