Hewes makes/made SS reels in different versions, for different tanks. Generally speaking, you need to match the type of reel to the type of tank - in some cases there is more than one maker of compatible tanks. As an example, Paterson and Arista/AP/Samigon plastic tanks and reels are compatible.
In my experience, the most common form of SS reel - including the most common Hewes reels - are designed to fit in tanks without centre cores. At one time, there were many competing types of tanks designed for those reels.
On the used market, be cautious about identifying the relatively rare oversized tanks, designed for larger film formats, like 220, on larger reels.