Before you can estimate demand, you'll need to consider who your customers will be.
Hire shop customers fall into two main groups with different needs - trade customers like builders and landscapers, and private householders. Trade customers will often want to hire larger items - for example, local building firms may need to make occasional use of an excavator, scaffolding tower or other plant equipment. Private householders (and some of the smallest construction businesses - typically self-employed trades-people who work on their own) are more likely to be looking for smaller items to undertake a DIY project at home - for example a floor sander, garden rotavator or electric cement mixer, although they might occasionally wish to hire larger pieces of equipment too.
To attract trade customers you will need the financial resources and space to buy and store large pieces of machinery. Heavy plant equipment is expensive, requires costly maintenance and will need a large yard or covered storage area. Special vehicles may be needed to transport it to and from sites too. As a result, some small hire businesses concentrate on the domestic/small trades-person end of the market as the tools commonly hired are smaller, cheaper to buy and easier to store and maintain.
While private customers may be prepared to pick up smaller items of hire equipment from your outlet, trade customers may expect a delivery service to their sites. They will expect this to be prompt and efficient - and not too expensive.
There is a lot of overlap between the two sectors, however, and you may decide to target a mixture of both trade and domestic customers. Some smaller firms offer small plant equipment such as mini diggers and excavators and, if necessary, will occasionally hire in a large piece of equipment which a customer needs.