[header] How to install foam bicycle tires [title] Let the air out of the pneumatic tire. [title] Insert a tire iron, or any tool with a slender handle and no sharp edges, under the lip of the tire. [substeps] Some companies include an installation paddle with the tires, or sell them separately. 
If you don't have one, just find another long, durable object you can use as a lever. A tire iron or oversize screwdriver should work.