Small Black Vinyl Tire for Grooved Rim: 3/4″ Wide All tires are made from durable vinyl. Vinyl tires will not leave black marks on patio floors like rubber tires. This tire is designed to fit a grooved rim. The tire size is determined by measuring the diameter of the rim. Tires are made slightly smaller than the rim for a tight fit. They are heated and stretched over the rim and into the groove. **** HOW TO INSTALL**** To install tires, you need to heat up the tire in boiling water. Place it over the rim and into the groove, then use a rubber mallet or any heavy device to press the tire into place until fully seated.