When it comes to your car, oil isn't the only thing there's a finite supply of. Rubber has its limits too, and it's estimated by 2020, the supply of natural rubber in the world may be outstripped by demand. And of course, tires require a great deal of oil to produce as well. Tire manufacturers are constantly looking for ways to innovate and conserve resources in tire production. Here are some recent advances:

• Dandelions: Yes, those humble yellow flowers you try to eliminate from your yard. Dandelions actually contain a minute amount of latex in their milky oil, and research shows they can actually produce about as much latex, pound-for-pound, as rubber plants. German scientists have cultivated 1-foot-tall dandelions for just this purpose. This isn't a new development, either -- in WWII, American companies were growing and cultivating Russian dandelions to cope with rubber scarcities due to wartime conditions.
• Silica: Tires are a complex blend of many different ingredients. Tires require friction for traction and control, but too much friction means heat buildup and rolling resistance, which hurts fuel economy. Engineers have discovered that mixing silica, the main ingredient in sand, in with carbon black and other elements can cut rolling resistance for better gas mileage. Too much silica means poor tread wear and traction, but manufacturers are aiming to strike the right balance between silica and carbon black in recent designs.
• Orange oil: In the search for alternatives to fossil fuels, a major manufacturer has taken the lead in using oil derived from orange peels in tire formulations. Orange oil has been used in cleaning products and other applications for years, but engineers have now figured out how to use it for lowered rolling resistance and better flexibility in tires.
• Soybean oil: While it's still in the development stages, it has been discovered that soybean oil can add up to ten percent to tire life, and can reduce fossil fuel use by up to 8.5 million gallons per year.
• Recycling: Vulcanization of rubber has been around since the 1830s. Vulcanized rubber is harder and more serviceable, but unfortunately vulcanization also means rubber which can't be recycled into tires again. Ironically, the same source that discovered this process has now uncovered a means to "de-vulcanize" rubber so it can be recycled for tire use. Currently, the recovery rate is about 80 percent; if the process can be scaled for mass-market use, it could mean a great solution for recycling the 800 million tires which are scrapped every year.