Racing tires are intended to be used for a limited time. After removing the tire from the vehicle, the tire expert uses a torch to heat up the built-up rubber on the tire, allowing him to remove it and expose three small holes on the tire known as wear pins. This process is called "scraping" the tire. The term "tire yard" describes a facility where racing tires are kept in stock so that they can be delivered quickly to race teams when needed. The purpose of storing tires is so that they are available whenever a team needs them. Tires also can be stored for other reasons; for example, they may need to be replaced due to wear or damage. As part of cleaning off their car before a race, nascar drivers will often scrape off any debris that might have accumulated during practice or qualifying heats. This includes any loose gravel or asphalt that might come off of the track during use. Scraping also helps the driver see any problems with his car that aren't readily apparent at first glance. Finally, scraping removes any residue from the manufacturing process that could cause problems later on. For example, if there's carbon black in the rubber, the driver would want to make sure it doesn't get into his eye. During prerace inspections, NASCAR officials will inspect each tire for defects.