New York City's fleet vehicles vary from four tires on a sedan to 10 on a garbage truck with approximately 140,000 tires on the road supporting on and off-road fleet. Because of the number of vehicles being used, tire tread has to regularly be checked. This is where the penny test comes in. 

Place a penny into a tire tread on a car, with the Lincoln head first. If Lincoln’s entire head is visible, the tread is too thin and the tire should be replaced.

But what happens to the particles and tire components as tires wear down? These particles can end up in streets, the ground, water, and air.

A series of tests found that emissions of particulate matter from tire wear can be 1,000 times worse than from tailpipes, according to Emissions Analytics, an organization that conducts independent emissions tests.

Using Soy-Based Biotires

To reduce the percentage of petroleum product used in vehicle tires, New York City Department of Citywide Administrative Services (DCAS) has partnered with the Clean Fuels Alliance to introduce soy-based biotires. Since 2018, fleet agencies, led by NYPD, have procured 1,931 light duty tires manufactured with soy products, according to DCAS, which first reported on this initiative in August 2020.

According to the DCAS supplier, soy oil can displace up to 60% of the petroleum used in these light duty tires. In 2023, the Department of Sanitation, the Department of Parks and Recreation, the Department of Environmental Protection and Department of Correction will introduce the first heavy duty tires using soy as an alternative to petroleum.  

Tire Particle Emissions

In addition to offsetting petroleum use in tires, DCAS is interested in whether these soy tires can help with the tire particle emissions. The City of New York and the City of London launched a fleet partnership in 2017 aimed at best practices in sustainability, safety, and efficiency. 

DCAS has also partnered with Emissions Analytics to study the particle emissions from sample city fleet tires and soy-based tires. DCAS has recently provided 83 used tires from 13 separate manufacturers to Emissions Analytics, including soy- and non-soy tires. Emissions Analytics will be looking at the organic chemical profiles for each to assess their tire emissions. 

DCAS will also be looking at driving patterns in correlation to vehicle emissions while working to address both the emissions that go into making tires and those that emit from the tires themselves.