- What the 19 Domains Actually Are
- Foundation Modules: Introduction Through Road Service Safety
- Inspection and RIST: The Heart of Wheel Safety
- Hub-Pilot, Stud-Pilot, and Demountable Rim Service
- Single Piece and Multi-Piece: Mounting, Demounting, and Inflation
- Balance, Repair, Charts, and USTMA Guidelines
- Domain Groups at a Glance
- Sequencing Your Preparation by Domain
- Who Benefits From This Credential
- Frequently Asked Questions
- The Commercial Tire Service 300 Level curriculum is organized into 19 modules published by the Tire Industry Association (TIA).
- These 19 modules are unweighted preparation topics, not an official percentage-based exam blueprint.
- Certification requires passing the final examination plus witnessed, signed-off demonstrations of shop skills.
- Safety content (OSHA 29 CFR 1910.177, RIST, safe inflation) runs through the entire curriculum.
What the 19 Domains Actually Are
The Commercial Tire Service 300 Level credential, issued by the Tire Industry Association, is built on a curriculum of 19 modules. TIA lists them under the Certified CTS 300/400 Level section of its Commercial Tire Service program page. This guide walks through each one so you know what to expect and where to spend your preparation time.
Before going further, it helps to be precise about what these 19 items represent. They are the issuer's own curriculum headings. They are not an exam blueprint with published percentage weights, and TIA's public materials do not state how many questions come from each module. Older descriptions of this program sometimes referred to 18 modules; the current list has 19, and that is the list this article follows.
TIA describes Certified CTS as designed for experienced employees with at least two years of hands-on experience. That wording comes straight from the issuer, and it tells you something about the style of the material: the curriculum assumes you have already touched real commercial wheels and tires, and it asks you to explain the correct, standardized way to do work you may already do every day. If you want the full picture of prerequisites, read CTS Requirements 2026: Eligibility, Prerequisites & How to Qualify.
Foundation Modules: Introduction Through Road Service Safety
The first five modules set the vocabulary and the safety framework for everything that follows.
Domain 1: Introduction
This module orients you to the program and to the responsibilities of a commercial tire service technician.
- Expect the course framing, terminology, and the expectations placed on a certified technician.
- Use it to learn the language the later modules rely on.
Domain 2: Tires
Commercial tires are the subject here: how they are constructed, identified, and applied.
- Be able to read sidewall information and recognize tire types and applications.
- Understand how construction and application affect service decisions later in the process.
Domain 3: Rims, Wheels & Hubs
This module covers the wheel system the tire sits on. TIA's own program materials emphasize wheel-system identification, and this is where that skill is built.
- Distinguish between wheel and rim configurations used on commercial vehicles.
- Know how the wheel, rim, and hub relate, because the later service modules (hub-pilot, stud-pilot, demountable) depend on correct identification.
Domain 4: OSHA Regulations
Regulation is a named module, not a side note. TIA's program documents specifically reference OSHA 29 CFR 1910.177, the standard governing servicing of multi-piece and single-piece rim wheels.
- Understand why the standard exists and what it requires of employers and technicians.
- Be ready to connect regulatory requirements to the specific procedures taught in later modules, such as inflation.
Domain 5: Road Service Safety
Commercial tire work often happens on the shoulder of a road rather than in a bay. This module addresses the hazards that come with working roadside.
- Think through positioning, visibility, and protecting yourself and the public.
- Recognize that service-truck work is a distinct environment with its own risks.
Inspection and RIST: The Heart of Wheel Safety
Modules 6 through 8 form a tight cluster. They cover how you get the vehicle safely off the ground, how you evaluate what you find, and the fastening discipline that keeps wheels on the vehicle.
Domain 6: Jacking & Lifting, Lock-Out/Tag-Out
Lifting a loaded commercial vehicle is inherently hazardous, and this module treats it that way. Lock-out/tag-out belongs here because servicing equipment and vehicles safely means controlling hazardous energy and making sure a vehicle or system cannot be unexpectedly activated while you are working on it. Study the proper use of jacks and supports and the logic behind lock-out/tag-out, not just the steps.
Domain 7: Tire/Wheel Inspection
Inspection is where judgment enters. TIA's materials describe inspection and repair decisions as part of the curriculum, so expect this module to ask not only "what do you see?" but "what do you do about it?" Practice evaluating a tire and wheel assembly systematically and deciding whether it can be serviced, repaired, or must be removed from service.
Domain 8: RIST
RIST stands for Remove, Inspect, Snug, and Torque. It is a named, repeatable procedure for wheel fastening, and it is one of the most distinctive pieces of this curriculum.
Hub-Pilot, Stud-Pilot, and Demountable Rim Service
Modules 9 through 11 are parallel by design. Each addresses a different way commercial wheels are located and fastened to the vehicle, and each has its own correct service procedure.
Domain 9: Hub-Pilot Service
Hub-piloted wheels are centered on the hub rather than on the studs.
- Learn how this mounting style positions the wheel and what that means for installation.
- Connect the procedure back to RIST.
Domain 10: Stud-Pilot Service
Stud-piloted wheels are located by the stud and nut arrangement.
- Understand how the fastening hardware does the centering work.
- Be ready to contrast stud-pilot and hub-pilot procedures, since a question may test whether you can tell them apart.
Domain 11: Demountable Rim Service
Demountable rims are a different system again, and they require their own procedure.
- Know how a demountable rim assembly is secured and serviced.
- Pay attention to the hardware and the sequence, since errors here carry real safety consequences.
The skill the program is building across these three modules is system recognition. Correct service starts with correctly identifying what you are looking at. A technician who treats every wheel the same will eventually make a dangerous mistake, and the curriculum is designed to prevent that.
Single Piece and Multi-Piece: Mounting, Demounting, and Inflation
Modules 12 through 15 are organized by wheel type, and each type gets a pair: one for mounting and demounting, one for inflation. Keeping that pairing in mind makes the material easier to organize.
- Domain 12: Single Piece Demount & Mount - procedures for removing and installing tires on single-piece wheels.
- Domain 13: Single Piece Inflation - safe inflation practices for single-piece assemblies.
- Domain 14: Multi-Piece Demount & Mount - procedures for multi-piece wheel assemblies.
- Domain 15: Multi-Piece Inflation - safe inflation practices specific to multi-piece assemblies.
Safe inflation is called out explicitly in TIA's program documents, and it ties directly to the OSHA module earlier in the curriculum. Multi-piece wheels have a well-known reputation for hazard during inflation because of the potential for components to separate violently if something is wrong. When you study Domains 14 and 15, keep the regulation from Domain 4 in your head and ask how each procedural step reduces that risk.
Key Takeaway
Do not study single-piece and multi-piece as one blob. Build a side-by-side comparison of how each wheel type is demounted, mounted, and inflated, and note which safety measures apply to which. Exam scenarios often hinge on knowing which procedure belongs to which wheel type.
Because the credential also requires witnessed, signed-off demonstrations of shop skills, these four modules are where hands-on practice pays off twice: once for the written final examination and again for the practical sign-offs.
Balance, Repair, Charts, and USTMA Guidelines
The last four modules cover quality, repair judgment, reference material, and industry guidance.
Domain 16: Balance & Run-Out
Balance and run-out affect ride quality, wear, and vehicle behavior.
- Understand what imbalance and run-out are and how they show up.
- Know how to evaluate and address them as part of a complete service.
Domain 17: Repair
Repair connects back to inspection. The curriculum treats repair as a decision as well as a procedure.
- Know when a tire is repairable and when it is not.
- Be able to follow the correct repair method once that decision is made.
Domain 18: Charts & Tables
This module is about reading reference data accurately. TIA's program materials specifically mention load and inflation tables.
- Practice looking up load capacity against inflation pressure and interpreting the result.
- Expect to apply a table to a scenario rather than simply recall a number.
Domain 19: USTMA Guidelines
The final module addresses guidance from the U.S. Tire Manufacturers Association, the industry body that publishes recommendations on tire care and service.
- Know that manufacturer-association guidance informs best practice alongside regulation.
- Be ready to apply it as the reference point for correct handling and service.
Charts & Tables deserves special mention for candidates who prefer hands-on work to reading. Table lookup is a skill, and it improves quickly with repetition. Our CTS Cheat Sheet 2026: One-Page Review of Must-Know Facts is a good place to consolidate the quick-reference items once you have worked through the full material.
Domain Groups at a Glance
The table below groups the 19 modules by the kind of knowledge they require. The grouping is an organizational aid for studying, not an official categorization or weighting from TIA.
| Group | Modules | Primary Skill |
|---|---|---|
| Foundations | 1-3 | Terminology and identification of tires, rims, wheels, and hubs |
| Safety and regulation | 4-6 | OSHA 29 CFR 1910.177, road service safety, lifting, lock-out/tag-out |
| Inspection and fastening | 7-8 | Inspection decisions and the RIST procedure |
| Wheel-system service | 9-11 | Hub-pilot, stud-pilot, and demountable rim procedures |
| Mount, demount, inflate | 12-15 | Single-piece and multi-piece tire handling and safe inflation |
| Quality and reference | 16-19 | Balance and run-out, repair, load/inflation tables, USTMA guidance |
Sequencing Your Preparation by Domain
Generic study advice is easy to find, so here is a sequence that follows the logic of this specific curriculum. The order matters because later modules assume you have mastered earlier ones. For a fuller approach, see the CTS Study Guide 2026: How to Pass on Your First Attempt.
Identification and Safety Framework
- Work through Domains 1-5, focusing on wheel-system identification and the intent of OSHA 29 CFR 1910.177.
- Why first: every later procedure depends on correctly identifying the wheel type.
Lifting, Inspection, and RIST
- Cover Domains 6-8, memorizing RIST and the reason behind each step.
- Why here: RIST is reused in every wheel-service module that follows.
Wheel-System and Tire Handling Procedures
- Study Domains 9-15, building side-by-side comparisons of hub-pilot, stud-pilot, demountable, single-piece, and multi-piece procedures.
- Why the most time: this is the largest block of procedural content and the closest match to the practical sign-offs.
Quality, Repair, and Reference
- Finish Domains 16-19, practicing load and inflation table lookups until they feel routine.
- Close with a full review pass across all 19 modules.
Adjust the pace to your own experience. A technician who changes multi-piece tires every week may move quickly through Domains 14 and 15 but need extra time on regulation and tables. Someone newer to roadside work may do the opposite. When you are ready to test yourself, use the CTS practice tests to find which modules still need attention.
Who Benefits From This Credential
The curriculum is aimed at people who do commercial tire work for a living: technicians in commercial tire shops, road service operators, and fleet maintenance staff who handle heavy-vehicle wheels. Because the material emphasizes regulation, inspection, and safe procedure, employers with an interest in reducing wheel-related incidents and documenting trained personnel are the natural audience. If you are weighing the investment, our Is the CTS Certification Worth It? Complete ROI Analysis 2026 breaks down the practical value, and CTS Jobs covers the roles where this training is relevant.
Keep in mind a few program mechanics from the issuer. The 300-Level technician course must be conducted by a TIA 400-Level Instructor, and certification depends on both the final examination and the witnessed demonstrations. TIA's public sources do not state the technician exam's question count, time limit, or numerical passing score, so be cautious about any site that claims specific figures. For what is and is not publicly known, see CTS Passing Score 2026: Exactly What You Need to Pass, and for scheduling questions see CTS Exam Dates 2026: Testing Windows, Deadlines & Scheduling.
Frequently Asked Questions
The current TIA curriculum lists 19 modules, from Introduction through USTMA Guidelines. Older descriptions referred to 18 modules, so make sure any study material you use reflects the current list.
No weighting is published. The 19 items are the issuer's curriculum headings and should be treated as unweighted preparation modules rather than an official exam blueprint with percentage allocations.
Both. Certification requires successful completion of the final examination and witnessed, signed-off demonstrations of shop skills. The mounting, inflation, and RIST modules are especially relevant to the practical portion.
Recertification is required every two years through an online examination. TIA maintains a dedicated recertification page for Commercial Tire Service where renewal access is provided.
Start with CTS Certification Cost 2026: Complete Pricing Breakdown for fee context and CTS Pass Rate 2026: What the Data Shows for what is and is not publicly reported. For the official program page, consult the Tire Industry Association directly.