While your refrigerator can now alert you when you are low on milk, the way we check tire tread depth with the penny tire test, is monitoring technology that is slightly ahead of the icebox age. Tires are the only part of a vehicle that touch the road and have the most significant impact on safety; yet, there is only one data point of information obtained to monitor tire health: tire pressure supplied by either a tire pressure sensor or TMPS sensor.
TPMS System Paves the Way for Tire Safety Improvements
Since 2005, the U.S. Department of Transportation (DOT) has required every new vehicle be equipped with a Tire Pressure Monitoring System (TPMS) to increase safety and reduce the number of low tire pressure-related accidents . Before the government established this regulation, it was well known that underinflated tires were a safety hazard. In fact, since the 1970s, there has been interest in monitoring tire pressure that did not require a handheld gauge or technician. The challenge was the lack of sufficient TPMS sensor technology to accomplish this. With the arrival of pressure sensing technology, along with the corresponding electronics and battery power, this market has been addressed.
Catalytic events brought greater attention to tire safety matters—most prominent was the infamous Ford Explorer – Firestone Tire rollover issue in the 1990s, where a combination of low recommended tire pressure and vehicle design flaws led to thousands of injuries and at least 250 deaths . Needless to say, the US government’s decision to mandate all vehicle models from the 2008 year on have a TPMS system installed was a tremendous boon for both the safety of vehicles and the commercialization of tire pressure monitoring systems.
TPMS sensor mandated
The remaining prominent tire-related safety challenge is the wear of tire tread thickness (the tire tread depth), which determines traction and stopping distance. Existing US federal government regulation establishes 2/32” as a minimum tire tread depth for safe vehicle use . While the critical nature of tire tread wear measurement is acknowledged at the policy level, implementation of a way to check tire depth has not advanced much beyond the use of a penny to determine tread depth. Hold a penny in one of the grooves or use a tread-depth gauge—a small handheld device rarely owned are the two primary ways to determine whether 2/32” of tread still remains. Needless to say, these techniques are seldom used and the result is a lot of worn out tires on the road—at least 10% of vehicles examined in a US National Highway Traffic Safety Administration (NHTSA) study proved to have dangerously worn tires. There is a pressing and completely unmet need for real-time tire tread monitoring in consumer and commercial vehicles to improve safety, efficiency, and performance. Consider the implications of 1 in every 10 vehicles having their stopping distance or traction severely compromised. The likelihood of tire-related crashes increases from just 2.4% to a staggering 26% when tires go from having full to worn-out tread . According to NHTSA and the US National Transportation Safety Board (NTSB), each year there are more than 700 deaths and thousands of injuries from tire-related crashes, most of which were preventable with sufficient tire health [5-7].
In addition to considerable safety improvements, a tire monitor similar to a TPMS sensor that addresses tire tread wear; a tire tread monitoring system (TTMS) would have considerable implications for enhanced tire efficiency. Thickness of remaining tread impacts how a tire flexes under the heat and strain of operation and thereby affects a vehicle’s fuel consumption . While a thicker tread may slightly increase a tire’s rolling resistance, unevenly distributed tread from tire to tire can compromise fuel economy, as will tire slippage due to poor traction.
More than 200 million passenger car tires are sold in the US each year. The timing and need for tire replacement on these vehicles could be more efficiently tracked with an integrated TTMS. Beyond passenger vehicles, there are millions of trucks in the shipping and transportation industry. These fleets incur hundreds of millions of dollars in tire-related expenses each year; hence, improvement in tire tread monitoring technology in the form of a tire tread sensor and added efficiency of more timely tire replacement, would have substantial economic benefits for fleet management companies.
Penny tire test
As we progress with the integration of autonomous vehicles on our roadways, there is a critical need for ensuring these vehicles are safely monitored without human intervention. There are consequences related to safety, efficiency, and profitability with insufficient monitoring of an autonomous vehicle’s tire tread depth. Hence, there is a burgeoning need for tire tread depth sensors in order to enable the autonomous vehicle revolution.
Autonomous tire tread sensor
Measuring tire tread depth has been of great interest to the industry for years. While there have been suggestions for achieving this measurement using complex algorithms based on data that is collected from a multiplicity of sensors, this results in only an approximation of tire tread wear that relies on many assumptions and variables that change in time. Others have explored the integration of materials or electrodes within the actual tread of a tire; yet, such an invasive approach lacks versatility and can compromise tire treadwear—a rating of how robust a tire’s tread will be, or the rate at which it will wear out. What is needed is a noninvasive way for directly and accurately measuring the thickness of a tire’s tread in real time and with applicability to any type of tire.
New tire tread depth
Tyrata, Inc. is commercializing the IntelliTread™ tire tread depth sensor, a simple device that is capable of measuring the tread thickness from within a tire (without being integrated into, or otherwise disrupting the tire itself). LEARN MORE
Target markets for this tire tread wear monitoring sensor include consumer vehicles (via tire & vehicle manufacturers) as well as commercial fleets, where not only improved safety, but enhanced efficiency of tire use is imperative. There is no competing technology available for remotely and directly measuring tire tread depth in real time, making this a trendsetting innovation. Further, this technology opens the way for data analytics on tire tread wear based on vehicle, geography, and other conditions, which would transform the efficiency of tire design and use across the industry.
The IntelliTread™ tire sensor has the potential to impact the entire value chain, from tire manufacturers all the way to end-users. For manufacturers, the value proposition is simple: sensors in tires create a differentiated offering that can command a higher price, especially if the sensor is proprietary. For middlemen, like distributors and dealers, the sensor offers a path towards selling more tires. For consumers, the value is primarily in safety, whereas for commercial end-users, the sensor offers a path to higher economic efficiency as tire use can be operated all the way to end-of-life without compromising safety.
Tire tread wear sensor
 “Department of Transportation Federal Motor Vehicle Safety Standards; Tire Pressure Monitoring Systems; Controls and Displays,” National Highway Traffic Safety Administration 49 CFR Parts 571 and 585, 2005. [Online]. Available: https://www.nhtsa.gov/sites/nhtsa.dot.gov/files/tpmsfinalrule.pdf
 M. Grayen, “What Is The History Of Tire Pressure Monitoring Systems?,” CARiD, 2016. [Online]. Available: https://www.carid.com/articles/what-is-history-of-tire-pressure-monitoring-systems.html
 “Tire Specs Explained: Tread Depth,” Tire Rack - Tire Tech, 2018. [Online]. Available: https://www.tirerack.com/tires/tiretech/techpage.jsp?techid=197
 “How safe are worn tires?,” Consumer Reports, 2014. [Online]. Available: https://www.consumerreports.org/cro/2012/12/how-safe-are-worn-tires/index.htm
 C. A. Hart, “Special Investigation Report: Selected Issues in Passenger Vehicle Tire Safety,” National Transportation Safety Board, 2015. [Online]. Available: https://www.ntsb.gov/news/events/Documents/2015_tiresafety_BMG_presentations.pdf
 "Tires," National Highway Transportation Safety Board. [Online]. Available: https://www.nhtsa.gov/equipment/tires
 "NHTSA Gets Real on Tire Fatalities," National Highway Transportation Safety Board. [Online]. Available: http://www.safetyresearch.net/blog/articles/nhtsa-gets-real-tire-fatalities
 P. Abelson, “Tires and fuel economy,” Land Line Mag, 2001. [Online]. Available: http://www.landlinemag.com/Magazine/2000/DecJan/BottomLine/52.aspx
IntelliTread tire depth sensor