Application Note | Tire Tread Inspection
Tire Tread Depth and Rubber Surface Roughness Measurement Using a 3D Optical Profiler
Measuring Tread Depth, Groove Contour, and Rubber Roughness in One Non-Contact Scan
Research & Experimental Testing
Andrea Herrmann
Visual Design & Editorial
Andrew Shore
Introduction
While tire tread depth is commonly measured with handheld gauges for consumer safety, industrial R&D and tire manufacturers require more advanced methods. This application note demonstrates how a 3D optical profilometer provides precise tire tread depth measurement, contour mapping, and rubber surface roughness analysis for high-accuracy studies.
Like all materials, rubber’s coefficient of friction is related in part to its surface roughness. In vehicle tires, both tread depth and surface roughness directly affect traction, braking, and wear performance. In this study, the rubber surface and tread’s roughness and dimensions are analyzed using 3D non-contact profilometry.
Why 3D Non-Contact Profilometry Matters for Tire Tread Depth Measurement
Unlike other techniques such as touch probes or interferometry, NANOVEA’s 3D Non-Contact Optical Profilers use axial chromatism to measure nearly any surface.
The Profiler system’s open staging allows for a wide variety of sample sizes and requires zero sample preparation. With a single scan, users can capture both overall tire tread depth and micro-level surface roughness, with zero influence from sample reflectivity or absorption. Plus, these profilers have the advanced ability to measure high surface angles without requiring software manipulation of results.
This versatility makes NANOVEA profilers ideal for both tire tread wear testing and advanced rubber material research.
ℹ️ Learn more about non-contact profilometry lab services for rubber and tires.
The Sample
Measurement Objective
In this application, we showcase the NANOVEA ST400, a 3D Non-Contact Optical Profiler measuring tire tread depth, contour geometry, and rubber surface roughness. A sample surface area large enough to represent the entire tire surface was selected at random for this study. To quantify the rubber’s characteristics, we used the NANOVEA Ultra 3D analysis software to measure groove dimensions, tread depth, surface roughness, and developed vs. projected area.
NANOVEA ST400 Standard
Optical 3D Profilometer
Analysis: Tire Tread
The 3D View and False Color View of the treads show the value of mapping 3D surface designs. This provides engineers with a straightforward tool to evaluate tread depth uniformity, groove design, and wear from multiple angles. The Advanced Contour Analysis and Step Height Analysis are both extremely powerful tools for measuring precise dimensions of sample shapes and design.
Fig. 1: False color view and 3D view of the tire tread.
Advanced Contour Analysis
Step Height Analysis
| Groove depth | Step 1 | Step 2 |
|---|---|---|
| Maximum height | 3.228 mm | 3.235 mm |
| Mean height | 3.182 mm | 3.206 mm |
Fig. 3: Step height analysis of two tread grooves.
| Groove depth | Step 1 |
|---|---|
| Maximum height | 3.574 mm |
| Mean height | 3.553 mm |
Fig. 4: Step height analysis of the wide tread groove.
Analysis: Rubber Surface
The rubber surface can be quantified in numerous ways using built-in software tools as shown in the following figures. It can be observed that the surface roughness is 2.688 µm, and the developed area vs. projected area is 9.410 mm² vs. 8.997 mm². These results demonstrate how rubber surface roughness affects traction and performance, enabling comparisons between different rubber formulations or varying levels of surface wear.
Fig. 5: False color view and 3D view of the rubber surface.
| Parameter | Value | Description |
|---|---|---|
| Sa | 2.688 µm | Arithmetic mean height |
| Sq | 3.657 µm | Root-mean-square height |
| Ssk | −1.60 | Skewness |
| Sku | 7.908 | Kurtosis |
| Sp | 13.35 µm | Maximum peak height |
| Sv | 26.10 µm | Maximum pit height |
| Sz | 39.45 µm | Maximum height |
| Spar | 8.997 mm² | Projected area |
| Sdar | 9.410 mm² | Developed area |
Table 1: ISO 25178 height parameters and other 3D parameters of the tire rubber surface.
Conclusion
In this application, we have shown how the NANOVEA 3D Non-Contact Optical Profiler can precisely characterize tire tread depth, contour dimensions, and rubber surface roughness. The data shows a surface roughness of 2.69 µm and a developed area of 9.41 mm² with a projected area of 9 mm². Various dimensions and radii of the rubber treads were measured as well. This information can be used by tire manufacturers, automotive researchers, and materials engineers to compare tread designs, rubber formulations, or tires with varying degrees of wear. The data shown here represents only a portion of the calculations available in the Ultra 3D analysis software.
Frequently Asked Questions About Tire Tread Depth Measurement
Why use 3D profilometry for tire tread depth instead of a gauge?
Handheld gauges suit consumer safety checks, but tire R&D and manufacturing need more. A 3D optical profilometer maps tread depth, groove contour and rubber surface roughness in high resolution, to evaluate depth uniformity, groove design and wear from multiple angles.
How does surface roughness relate to tire performance?
Like all materials, rubber’s coefficient of friction is related in part to its surface roughness. In tires, both tread depth and surface roughness directly affect traction, braking and wear performance.
How is tread groove depth measured?
Step Height Analysis on profiles extracted from the 3D scan. Here two grooves measured maximum heights of 3.228 and 3.235 mm (mean 3.182 and 3.206 mm), and a wider groove 3.574 mm maximum (3.553 mm mean).
What does contour analysis measure on a tread?
Advanced Contour Analysis measures precise dimensions of the tread shape from a profile, such as groove widths, step heights, wall angles and radii.
What surface roughness was measured on the tire rubber?
An arithmetic mean height Sa of 2.688 µm (Sq 3.657 µm, Sz 39.45 µm), with a developed area of 9.410 mm² against a projected area of 8.997 mm².
Which NANOVEA instrument was used for tire tread measurement?
The NANOVEA ST400 3D Non-Contact Optical Profiler, which uses axial chromatism with open staging and no sample preparation, analyzed with the Ultra 3D software.
