WO2019241368A1

WO2019241368A1 - Methods of measuring and/or mapping tire tread thickness from outside the tire and related devices/systems

Info

Publication number: WO2019241368A1
Application number: PCT/US2019/036742
Authority: WO
Inventors: Joseph Batton Andrews; Aaron Daniel Franklin; David Alan Koester; James Barton Summers III
Original assignee: Tyrata, Inc.; Duke University
Priority date: 2018-06-14
Filing date: 2019-06-12
Publication date: 2019-12-19

Abstract

Methods of measuring thicknesses of a tire tread are discussed. An outside surface of a tire may be received on a tread sensor array, wherein the tread sensor array includes a plurality of tread sensors arranged across a width of the tire. For at least one of the plurality of tread sensors of the tread sensor array, a respective thickness associated with the at least one tread sensor may be determined. Related tread measuring systems are also discussed.

Description

METHODS OF MEASURING AND/OR MAPPING TIRE TREAD THICKNESS FROM OUTSIDE THE TIRE AND RELATED DEVICES/SYSTEMS

TECHNICAL FIELD

The present disclosure relates generally to tires, and more particularly, to tire sensors and related methods.

BACKGROUND

Currently, tire pressure sensors may be provided in vehicle tires. Such sensors may be used to automatically monitor tire pressure, and a warning (e.g., a warning light) may be provided to the driver when low pressure is detected. Other aspects of the tire, however, may require manual monitoring and failure to adequately monitor such aspects may cause issues relating to safety. Accordingly, improved monitoring of vehicle tires may be desired.

SUMMARY

According to some embodiments of inventive concepts, methods of measuring thicknesses of a tire tread may be provided. An outside surface of a tire may be received on a tread sensor array, wherein the tread sensor array includes a plurality of tread sensors arranged across a width of the tire. For at least one of the plurality of tread sensors of the tread sensor array, a respective thickness associated with the at least one tread sensor may be determined.

According to some other embodiments of inventive concepts, tire tread measuring systems may be provided. A tread sensor array may include a plurality of tread sensors on a substrate, wherein the tread sensor array is configured to receive a tire such that the plurality of tread sensors are arranged across a width of the tire. A controller may be coupled with the tread sensor array, wherein the controller is configured for at least one of the plurality of tread sensors of the tread sensor array to determine a respective thickness associated with the at least one tread sensor. BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate certain non-limiting embodiments of inventive concepts. In the drawings:

Figure 1A is a diagram illustrating design/manufacture of a sensory array according to some embodiments of inventive concepts;

Figure 1B is a photograph of a sensory array according to some embodiments of inventive concepts;

Figures 1C and 1D are scanning electron microscope images of a sensor of Figure 1B according to some embodiments of inventive concepts;

Figure 2A is a photograph illustrating a setup to measure a tire tread using a sensor array according to some embodiments of inventive concepts;

Figure 2B is a cross sectional view illustrating operations of a sensor according to some embodiments of inventive concepts;

Figure 3 is a graph illustrating Sn measurements for three active electrode pair positions according to some embodiments of inventive concepts;

Figures 4A and 4B are plots comparing Sn and actual tread thickness measurements according to some embodiments of inventive concepts;

Figure 5 is a plot of Sn correlated with a full width of a tire according to some embodiments of inventive concepts;

Figure 6 is a photograph illustrating a tread sensor array printed on a circuit board according to some embodiments of inventive concepts;

Figure 7 is photograph illustrating shifts in frequency for an impedance matching condition according to some embodiments of inventive concepts;

Figure 8 is a block diagram illustrating elements of a system to analyze tire tread patterns according to some embodiments of inventive concepts; and

Figure 9 is a flow chart illustrating operations of a system according to some

embodiments of inventive concepts.

DETAIFED DESCRIPTION Inventive concepts will now be described more fully hereinafter with reference to the accompanying drawings, in which examples of embodiments of inventive concepts are shown. Inventive concepts may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of present inventive concepts to those skilled in the art. It should also be noted that these embodiments are not mutually exclusive. Components from one embodiment may be tacitly assumed to be present/used in another embodiment.

The following description presents various embodiments of the disclosed subject matter. These embodiments are presented as teaching examples and are not to be construed as limiting the scope of the disclosed subject matter. For example, certain details of the described embodiments may be modified, omitted, or expanded upon without departing from the scope of the described subject matter.

An ability has been demonstrated in U.S. Patent No. 9,797,703 to non-invasively measure the thickness of a tire using an oscillating electrical signal between a pair of sensor electrodes located directly beneath a tread block, on the inside of the tire. The disclosure of US Patent No. 9,797,703 is hereby incorporated herein in its entirety by reference.

Some embodiments of present inventive concepts may use a similar sensor electrode structure and applied oscillating electrical signal but with the electrodes integrated into an array and used to measure the thickness of a tire’s tread from outside of the tire. With the array extending across the width of a tire, the tread thickness can be mapped for the various grooves and tread blocks. According to such embodiments, the array of electrodes is not attached to the tire, but instead, the vehicle drives over the array of electrodes, with the tread being measured as the tire passes over the array.

Measuring the thickness of a tire’s tread may be important to provide/ensure safe tire and vehicle conditions. Unlike tire pressure, tread depth does not change rapidly and can therefore be monitored much less frequently (on the order of weeks or months). Having a technology that is capable of measuring the thickness of a tire’s tread, across the width of the tire, may be desirable.

Existing technologies may involve the use of lasers and expensive corresponding equipment to measure the pattern of a tire’s tread. According to some embodiments of present inventive concepts, tread measurement may be provided using electrical signals from low-cost sensors that are, for example, either printed or plated (or otherwise fabricated using any other high-volume manufacturing approach). Some embodiments of inventive concepts may involve sensor electrodes that are assembled into an array, such as a linear array of square electrodes approximately 5 mm in size with a 0.15 mm gap between each electrode. By applying an oscillating electrical signal to one electrode and grounding the neighboring electrode, a measurement is taken of some measurable parameter (e.g., Sn signal reflectance, impedance, reactance, frequency of resonance, frequency of some matching condition, etc.). After taking such a measurement from each electrode pair in the array, the change in the measured parameter across the width of the tire is used to determine the thickness of the tread blocks. In this way, a cross-sectional map of the tread profile can be generated to provide information about the thickness of the tread and any unevenness of wear across the tire. Note that some form of algorithm or look-up table may be used to convert the measured signal change across a tire to the actual thickness of the tire tread.

Different embodiments of inventive concepts may be provided using an array of sensor electrodes. According to some embodiments, printed electrodes may be provided, and an Sn reflected signal magnitude may be used to measure the thickness across the width of a tire. According to some other embodiments, a shift in frequency at which a certain impedance condition is met may be used to provide a thickness measurement across the width of a tire. These embodiments illustrate that by applying an oscillating electrical signal between a pair of electrodes, there are several different parameters that can be used to derive the same outcome, which is the measurement of tire tread depth across a width of a tire. These parameters include S n, frequency shift at a specific impedance/reactance condition, impedance/reactance shift at a specific frequency, resonant frequency shift, and so forth. The parameter is measured and compared at different sensor pair locations across a tire, with the relative values of the parameters at different locations used to determine the thickness of the tire tread.

Figures 1A-D illustrate design and images of printed sensor array. Figure 1A

schematically illustrates an aerosol jet printing process with inset profile of an electrode, including a bottom layer of silver nanoparticles and a top layer of unsorted carbon nanotubes (CNTs). Figure 1B is a photograph of a fully printed sensor array. Figures 1C and 1D are scanning electron microscope (SEM) images of the sensing electrodes at different magnifications.

Figures 2A and 2B illustrate testing setup and operation. Figure 2A is a photograph of the sensor array placed on the outside of a tire and connected to a VNA (Vector Network Analyzer), which measures the signal reflectance between each electrode. Figure 2B is a cross-sectional view illustrating how the tests for each position may be completed; all electrodes to one side of an active electrode pair (200) are tied to signal (201) while those on the other side are tied to ground (202). An illustration of the fringing electric field lines (203) interacting with the tire (204) is also included.

Figure 3 is a graph illustrating Sn for three distinct active electrode pair positions (i.e., a gap between electrodes was centered either on a tread block, a groove, or a sipe). Sn with respect to frequency is shown for three sensor measurement points on the tire: full tread (thickest), sipes (or minor tread patterns), and the full grooves. The inset shows the active sensing frequency, which is directly below the second resonant frequency of the spectrum.

Figures 4A and 4B provide plots comparing measured Sn to actual tread thickness measurements. Figure 4A shows the Sn at 510 MHz (data points are averages with error bars indicating a 99% confidence interval), and Figure 4B shows the actual tread thickness measurement (measured using tire tread depth gauge). Note that the percent difference between each point is the same.

Figure 5 provides an Sn plot correlated with the full width of a non- worn tire. The Sn response of the tire array is tri-modal, with three distinct magnitudes that correlate with the full tread, the sipes, and the grooves. These measurements were taken using a stationary array positioned on the outside of the tire. An inset at the bottom of the plot shows the tire profile as it corresponds (approximately) with the position of the array during the measurements.

Figure 6 is a photograph of a tread sensor array on printed circuit board (FR4). In Figure 6, the tread sensor array includes 13 sensors, with each sensor including a grounded electrode and a signal electrode as discussed above with respect to Figure 2B. With the tread sensor array of Figure 6 on the ground (perpendicular to a direction of rolling of the tire), a tire may be driven onto the tread sensor array and stopped so that each sensor of the array is aligned with a different portion of the tread across a width of the tire. Figure 7 is a photograph of a tire illustrating a shift in frequency for a specific impedance matching condition, showing dependence on the location of the sensor, being either above tire grooves or on tire tread blocks. Sensors on a printed circuit board were used for this

embodiment.

Figure 8 is a block diagram illustrating a system to analyze tire tread patterns according to some embodiments including an analyzer and a tread sensor 807. The analyzer 800, for example, may provide functionality of the network analyzer VNA and/or the computer of Figure 2A, and the tread sensor 807 may be provided as discussed above with respect to Figures 2B and/or Figure 6. Moreover, tread sensor 807 may be coupled with controller 801 of analyzer 800 through interface 803. Moreover, modules may be stored in memory 805, and these modules may provide instructions so that when instructions of a module are executed by controller 801, controller 801 performs respective operations (e.g., operations discussed below with respect to the claims). Moreover, interface 803 may also provide coupling between controller 801 and an output device 809 (e.g., a display, printer, etc.) to provide output data to a user.

With tread sensor array 807 implemented as discussed above with respect to Figure 6, a tire may be driven onto the tread sensor array 807 and stopped. With the tire positioned on the array 807, controller 801 may apply an RF signal to each of the 13 sensors (either sequentially or in parallel) and measure the reflected signals from each sensor (i.e., pair of electrodes) to determine a tread thickness associated with each sensor. Accordingly, the individual sensors of tread sensor array 807 may be used to measure respective thickness of respective portions of the tread across the width of the tire. Results of the measurements may be provided by controller 801 through interface 803 to an output device 809 such as a display or printer. An alternative embodiment may be that a tire is driven over tread sensor array 807 without stopping and that the controller 801 operates as above to determine the tread thickness across the width of the tire in a manner that is fast enough to collect measurement data/information during tire motion, with the measurement triggered in some fashion as the tire comes into the vicinity of, or in contact with, the sensor array 807.

Figure 2B is a schematic diagram illustrating operation of an individual tread

measurement sensor of Figure 6 according to some embodiments of inventive concepts. In the illustration of Figure 2B, the tread measurement sensor is shown on an outside surface of the tire without the other elements of Figures 6/8 to more clearly illustrate operations thereof. Operation of the tread measurement sensor is based on the mechanics of how electric and magnetic fields interact with different materials. As shown in Figure 2B, the tread measurement sensor includes two electrically conductive sensor elements (also referred to as electrodes) side-by-side and very close to each other.

The controller 801 may thus apply an oscillating electrical voltage to one of the sensor elements (the signal electrode) of the sensor while the other sensor element (the grounded electrode) of the sensor is grounded to generate an electrical field between the two sensor elements (shown as arcs in Figure 2B). While most of the field may pass directly between edges of the electrodes, some of the field arcs from the face of one electrode to the face of the other electrode through the tire tread (shown by arcs in Figure 2B). The tire rubber and tread structure interfere with this“fringing field,” and by measuring this interference through the electrical response of the sensor electrode pair, the controller 801 may thus generate thickness parameter information associated with the respective tread portion of the tire. By performing the measurement at each sensor of tread sensor array 807, a profile of tread thickness may be provided across a width of the tire to determine tread thicknesses, wear patterns, etc.

Operations of the system of Figure 8 will now be discussed with reference to the flow chart of Figure 9 according to some embodiments of inventive concepts. For example, modules may be stored in memory 805 of Figure 8, and these modules may provide instructions so that when the instructions of a module are executed by controller 801, controller 801 performs respective operations of the flow chart.

At block 901, an outside surface of a tire may be received on tread sensor array 807 so that a plurality of tread sensors of tread sensor array 807 are arranged across a width of the tire. For example, the tire may roll across tread sensory array 807. Tread sensor array 807 may be provided as shown in Figure 6 with the row of tread sensors arranged in a direction perpendicular with respect to a direction of motion of the tire, with each tread sensor including a grounded electrode and a signal electrode.

At block 905, controller 801 may determine a respective thickness associated with at least one of the plurality of tread sensors of the tread sensor array. For example, controller 801 may apply (through interface 803) an oscillating electrical signal (e.g., a radio frequency RF oscillating signal) across the grounded and signal electrodes of each of the plurality of tread sensors (of tread sensor array 807) and measure a resulting electrical parameter from each of the plurality of tread sensors. The electrical parameter for a respective one of the tread sensors, for example, may be: a reflection of the oscillating electrical signal by the grounded electrode of the respective tread sensor; a frequency of the oscillating electrical signal at which an impedance condition is matched; an impedance or reactance value measured at a specific frequency of the oscillating electrical signal; and/or a frequency of resonance of the oscillating electrical signal.

At block 909, controller 801 may generate an output for an output device, wherein the output provides at least one of a tread thickness of the tire and/or a profile of tread thickness of the tire across a width of the tire determined based on relative changes in the electrical parameter from the tread sensors of the tread sensor array. The output device, for example, may be: a display such that generating the output comprises generating the output to be presented on the display; and/or a printer such that generating the output comprises generating the output to be printed from the printer.

In the above-description of various embodiments of present inventive concepts, it is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of present inventive concepts. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which present inventive concepts belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

When an element is referred to as being "connected", "coupled", "responsive", or variants thereof to another element, it can be directly connected, coupled, or responsive to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected", "directly coupled", "directly responsive", or variants thereof to another element, there are no intervening elements present. Like numbers refer to like elements throughout. Furthermore, "coupled", "connected", "responsive", or variants thereof as used herein may include wirelessly coupled, connected, or responsive. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Well-known functions or constructions may not be described in detail for brevity and/or clarity. The term "and/or" includes any and all combinations of one or more of the associated listed items.

It will be understood that although the terms first, second, third, etc. may be used herein to describe various elements/operations, these elements/operations should not be limited by these terms. These terms are only used to distinguish one element/operation from another

element/operation. Thus, a first element/operation in some embodiments could be termed a second element/operation in other embodiments without departing from the teachings of present inventive concepts. The same reference numerals or the same reference designators denote the same or similar elements throughout the specification.

As used herein, the terms "comprise", "comprising", "comprises", "include", "including", "includes", "have", "has", "having", or variants thereof are open-ended, and include one or more stated features, integers, elements, steps, components or functions but do not preclude the presence or addition of one or more other features, integers, elements, steps, components, functions or groups thereof. Furthermore, as used herein, the common abbreviation "e.g.", which derives from the Latin phrase "exempli gratia," may be used to introduce or specify a general example or examples of a previously mentioned item, and is not intended to be limiting of such item. The common abbreviation "i.e.", which derives from the Latin phrase "id est," may be used to specify a particular item from a more general recitation.

The dimensions of elements in the drawings may be exaggerated for the sake of clarity. Further, it will be understood that when an element is referred to as being "on" another element, the element may be directly on the other element, or there may be an intervening element therebetween. Moreover, terms such as "top," "bottom," "upper," "lower," "above," "below," and the like are used herein to describe the relative positions of elements or features as shown in the figures. For example, when an upper part of a drawing is referred to as a "top" and a lower part of a drawing is referred to as a "bottom" for the sake of convenience, in practice, the "top" may also be called a "bottom" and the "bottom" may also be a "top" without departing from the teachings of the inventive concept (e.g., if the structure is rotate 180 degrees relative to the orientation of the figure).

Example embodiments are described herein with reference to block diagrams and/or flowchart illustrations of computer-implemented methods, apparatus (systems and/or devices) and/or computer program products. It is understood that a block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented by computer program instructions that are performed by one or more computer circuits. These computer program instructions may be provided to a processor circuit of a general purpose computer circuit, special purpose computer circuit, and/or other programmable data processing circuit to produce a machine, such that the instructions, which execute via the processor of the computer and/or other programmable data processing apparatus, transform and control transistors, values stored in memory locations, and other hardware components within such circuitry to implement the functions/acts specified in the block diagrams and/or flowchart block or blocks, and thereby create means (functionality) and/or structure for implementing the functions/acts specified in the block diagrams and/or flowchart block(s).

These computer program instructions may also be stored in a tangible computer-readable medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable medium produce an article of manufacture including instructions which implement the functions/acts specified in the block diagrams and/or flowchart block or blocks. Accordingly, embodiments of present inventive concepts may be embodied in hardware and/or in software (including firmware, resident software, micro-code, etc.) that runs on a processor (also referred to as a controller) such as a digital signal processor, which may collectively be referred to as "circuitry," "a module" or variants thereof.

It should also be noted that in some alternate implementations, the functions/acts noted in the blocks may occur out of the order noted in the flowcharts. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality/acts involved. Moreover, the functionality of a given block of the flowcharts and/or block diagrams may be separated into multiple blocks and/or the functionality of two or more blocks of the flowcharts and/or block diagrams may be at least partially integrated. Finally, other blocks may be added/inserted between the blocks that are illustrated, and/or blocks/operations may be omitted without departing from the scope of inventive concepts. Moreover, although some of the diagrams include arrows on communication paths to show a primary direction of communication, it is to be understood that communication may occur in the opposite direction to the depicted arrows. Many variations and modifications can be made to the embodiments without substantially departing from the principles of the present inventive concepts. All such variations and modifications are intended to be included herein within the scope of present inventive concepts. Accordingly, the above disclosed subject matter is to be considered illustrative, and not restrictive, and the examples of embodiments are intended to cover all such modifications, enhancements, and other embodiments, which fall within the spirit and scope of present inventive concepts. Thus, to the maximum extent allowed by law, the scope of present inventive concepts are to be determined by the broadest permissible interpretation of the present disclosure including the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description.

Claims

CLAIMS:

1. A method of measuring thicknesses of a tire tread, the method comprising:

receiving an outside surface of a tire on a tread sensor array, wherein the tread sensor array includes a plurality of tread sensors arranged across a width of the tire; and

for at least one of the plurality of tread sensors of the tread sensor array, determining a respective thickness associated with the at least one tread sensor.

2. The method of Claim 1, wherein each tread sensor includes a grounded electrode and a signal electrode, and wherein determining comprises applying an oscillating electrical signal across the grounded and signal electrodes of each of the plurality of tread sensors and measuring a resulting electrical parameter from each of the plurality of tread sensors.

3. The method of Claim 2 further comprising:

generating an output for an output device, wherein the output provides at least one of a tread thickness of the tire and/or a profile of tread thickness of the tire across a width of the tire determined based on relative changes in the electrical parameter from the tread sensors of the tread sensor array.

4. The method of Claim 2, wherein the electrical parameter for a respective one of the tread sensors is a reflection of the oscillating electrical signal by the grounded electrode of the respective tread sensor.

5. The method of Claim 2, wherein the electrical parameter for a respective one of the tread sensors is a frequency of the oscillating electrical signal at which an impedance condition is matched.

6. The method of Claim 2, wherein the electrical parameter for a respective one of the tread sensors is an impedance or reactance value measured at a specific frequency of the oscillating electrical signal.

7. The method of Claim 2, wherein the electrical parameter for a respective one of the tread sensors is a frequency of resonance of the oscillating electrical signal.

8. The method of Claim 3, wherein the output device comprises a display, and wherein generating the output comprises generating the output to be presented on the display.

9. The method of Claim 3, wherein the output device comprises a printer, and wherein generating the output comprises generating the output to be printed from the printer.

10. The method of Claim 2, wherein the at least one tread sensor is a first tread sensor of the tread sensor array, wherein determining comprises applying a first oscillating electrical signal across the grounded and signal electrodes of the first tread sensor and applying a second oscillating electrical signal across the grounded and signal electrodes of a second tread sensor of the tread sensor array, wherein determining comprises measuring a first electrical parameter from the first tread sensor responsive to the first oscillating electrical signal and measuring a second electrical parameter from the second tread sensor responsive to the second oscillating electrical signal, and wherein determining comprises determining a thickness of a tread block based on a difference between the first and second electrical parameters.

11. The method of Claim 10, wherein the first tread sensor is adjacent the tread block and the second tread sensor is adjacent a groove in a pattern of the tire tread.

12. The method of Claim 1, wherein the tread sensor array is materially separate from the tire.

13. The method of Claim 2, wherein the oscillating electrical signal is a radio frequency (RF) oscillating electrical signal.

14. A tire tread measuring system comprising: a tread sensor array including a plurality of tread sensors on a substrate, wherein the tread sensor array is configured to receive a tire such that the plurality of tread sensors are arranged across a width of the tire; and

a controller coupled with the tread sensor array, wherein the controller is configured for at least one of the plurality of tread sensors of the tread sensor array to determine a respective thickness associated with the at least one tread sensor.

15. The tire tread measuring system of Claim 14, wherein each tread sensor includes a grounded electrode and a signal electrode, and wherein the controller is configured to determine the respective thickness associated with the at least one tread sensor by applying an oscillating electrical signal across the grounded and signal electrodes of each of the plurality of tread sensors and measuring a resulting electrical parameter from each of the plurality of tread sensors.

16. The tire tread measuring system of Claim 14, wherein the controller is further configured to generate an output for an output device, wherein the output provides at least one of a tread thickness of the tire and/or a profile of tread thickness of the tire across a width of the tire determined based on relative changes in the electrical parameter from the tread sensors of the tread sensor array.

17. The tire tread measuring system of Claim 15, wherein the electrical parameter for a respective one of the tread sensors is a reflection of the oscillating electrical signal by the grounded electrode of the respective tread sensor.

18. The tire tread measuring system of Claim 15, wherein the electrical parameter for a respective one of the tread sensors is a frequency of the oscillating electrical signal at which an impedance condition is matched.

19. The tire tread measuring system of Claim 15, wherein the electrical parameter for a respective one of the tread sensors is an impedance or reactance value measured at a specific frequency of the oscillating electrical signal.

20. The tire tread measuring system of Claim 15, wherein the electrical parameter for a respective one of the tread sensors is a frequency of resonance of the oscillating electrical signal.

21. The tire tread measuring system of Claim 16, wherein the output device comprises a display, and wherein generating the output comprises generating the output to be presented on the display.

22. The tire tread measuring system of Claim 16, wherein the output device comprises a printer, and wherein generating the output comprises generating the output to be printed from the printer.

23. The tire tread measuring system of Claim 15, wherein the at least one tread sensor is a first tread sensor of the tread sensor array, wherein determining comprises applying a first oscillating electrical signal across the grounded and signal electrodes of the first tread sensor and applying a second oscillating electrical signal across the grounded and signal electrodes of a second tread sensor of the tread sensor array, wherein determining comprises measuring a first electrical parameter from the first tread sensor responsive to the first oscillating electrical signal and measuring a second electrical parameter from the second tread sensor responsive to the second oscillating electrical signal, and wherein determining comprises determining a thickness of a tread block based on a difference between the first and second electrical parameters.

24. The method of Claim 23, wherein the first tread sensor is adjacent the tread block and the second tread sensor is adjacent a groove in a pattern of the tire tread.

25. The method of Claim 14, wherein the tread sensor array is materially separate from the tire.

26. The method of Claim 15, wherein the oscillating electrical signal is a radio frequency (RF) oscillating electrical signal.