Wheelbarrows generally have one of two tire sizes. Smaller ones have a 4.00-6 tire, and usually the tread has circumferential grooves, referred to in the industry as a “ribbed tread.” There are not a lot of options for this size.
The other size found on wheelbarrows is 480-8, sometimes written by tire manufacturers as 480/400-8. The tread pattern originally is almost always a ribbed tread. If your wheelbarrow has this type of tire and it served you well, by all means, replace it with the same type of tire. If not, you have some other options. A zig zag or “saw tooth” tread pattern allows you a choice of a larger air volume which translates into an easier rolling wheelbarrow.
If, when you go to use your wheelbarrow and the tire is flat, there is a great solution! A solid tire built by Amerityre Corporation eliminates flat tires. Since it is solid, it also rolls easier. It is offered in a tire and wheel assembly. You will need to know the hub bearing size and length of shaft on your wheelbarrow. The tire is very durable and may well outlast your wheelbarrow!