Tire tread depth plays a critical role in fleet safety, performance, and compliance. Understanding DOT regulations for tread depth and steer tire requirements is essential for commercial fleet managers. This guide covers key details about tire tread depth measurement, regulations, and how Motive’s solutions can support your fleet operations.

What is tire tread depth?

Tire tread depth measures the vertical distance from the top of the tread to the bottom of the grooves. In the United States, it’s measured in 1/32 of an inch, while metric systems use millimeters.

Tread depth affects vehicle performance, including traction, braking, and fuel efficiency. Worn tread can compromise safety, especially in rain or snow.

Key components of tire tread include:

  • Ribs: Raised bands around the tire.
  • Blocks/Lugs: Segments between the ribs.
  • Grooves: Spaces between ribs.
  • Voids: Gaps between tread blocks.
  • Sipes: Thin slits across tread blocks and ribs.

Why Is checking DOT tire tread depth important?

According to the Commercial Vehicle Safety Alliance (CVSA), tire and wheel violations are a top reason vehicles are taken out of service during inspections. Regular tire maintenance reduces these risks and improves fleet profitability.

Tread wear also provides valuable diagnostic insights:

  • Center tread wear: Indicates overinflation.
  • Shoulder wear: Points to underinflation.
  • Uneven wear on one side: Suggests alignment issues.

DOT steer tire regulations and requirements

The Federal Motor Carrier Safety Administration (FMCSA) mandates minimum tread depths for commercial trucks to meet the regulations in the Code of Federal Regulations § 393.75 

  • Steer tires: Minimum tread depth of 4/32 inch.
  • All other tires: Minimum tread depth of 2/32 inch.

CVSA requirements are slightly less stringent:

  • Steer tires: 2/32 inch minimum.
  • Other tires: 1/32 inch minimum.

Compliance with DOT steer tire regulations is critical for avoiding violations and maintaining fleet safety.

How to measure tire tread depth for DOT compliance

Use a tire tread depth gauge for accurate measurements. Alternatively, the penny test can provide a quick estimate:

  • Insert a penny into the shallowest groove with Lincoln’s head upside down.
  • If you can see all of Lincoln’s head, the tread depth is less than 2/32 inch.

For precise measurements, consult a commercial truck tire tread depth chart. Different truck tires have varying original depths based on application.

What to do about uneven tread depth

Irregular tread wear can signal:

  • Alignment issues.
  • Suspension problems.
  • Over- or underinflation.

To address uneven wear, rotate or replace tires, or consider retreading.

Optimize fleet tire health with Motive

Motive’s fleet safety and maintenance solutions help fleets monitor tire health and meet DOT requirements. Key features include:

  • Maintenance Reminders: Keep track of tire inspections and tread depth.
  • Driver Behavior Monitoring: Identify hard braking, cornering, and acceleration that contribute to tread wear.
  • Customizable Inspections: Tailor inspections for steer tires, trailers, and other vehicle types.

By understanding DOT tire tread depth regulations and prioritizing regular inspections, fleets can improve safety, cut costs, and stay compliant.

Learn how the Motive Integrated Operations Platform helps you stay on top of fleet safety and tire health today.