Timing Belt Number Meaning: How to Read Timing Belt Codes

Quick Answer

Timing belt number meaning usually depends on the belt manufacturer’s numbering system. A timing belt code may identify some combination of tooth count, tooth profile, pitch, belt width, or a manufacturer’s product reference, while an OEM number identifies the original vehicle or engine application.

For example, 163S8M27 can be read as:

• 163 = 163 teeth
• S8M = S8M tooth profile / 8 mm pitch
• 27 = 27 mm belt width
• 163 × 8 mm = 1,304 mm pitch length

However, timing belt numbers are not universally standardized. A code that looks similar between brands should not automatically be treated as interchangeable.

For automotive replacement belts, the safest identification sequence is:

Belt marking → OEM reference → vehicle/engine application → tooth profile → pitch → tooth count → width → cross-reference → supplier confirmation

This guide focuses specifically on how to understand, decode, verify, and cross-reference timing belt numbers, with 10 representative automotive timing belt examples.

1. What Does a Timing Belt Number Mean?

A timing belt number is not always a single standardized measurement code.

Depending on the manufacturer and belt series, a timing belt number may contain:

• Tooth count
• Tooth profile
• Tooth pitch
• Belt width
• Product family
• Manufacturer-specific identification
• Application reference
• OEM cross-reference information

This is why two timing belts with similar-looking numbers may have different applications.

For example:

163S8M27

contains technical information that can be interpreted as:

163 teeth + S8M profile + 27 mm width

By contrast, an OEM number such as:

Toyota 13568-03010

is primarily an application/reference number, rather than a direct dimensional description.

This distinction is important for aftermarket distributors because a replacement belt may have several different numbers referring to essentially the same application.

For a broader introduction to timing belt construction, selection, materials, and applications, see the Timing Belt Guide.

For example, the marking 163S8M27 timing belt shows how timing belt identification numbers describe tooth count, pitch and width. Understanding these codes helps buyers select the correct replacement belt.

2. Timing Belt Number vs Part Number vs OEM Number

One of the most common identification mistakes is treating every number printed on a timing belt as if it means the same thing.

There are three important categories.

These numbers can sometimes cross-reference to one another.

For example, a timing belt application may have:

OEM: Toyota 13568-03010
Technical-style number: 163S8M27
Aftermarket reference: Gates 5202XS

Therefore, distributors should not rely on only one number when establishing product equivalence.

A proper cross-reference should confirm:

OEM application + tooth profile + pitch + tooth count + width

The broader principles are also relevant to the Automotive Belt Cross Reference Guide.

3. How Automotive Timing Belt Numbers Are Structured

Automotive timing belt numbering often looks more complicated than it actually is.

A typical technical code may contain several pieces of information.

For example:

163S8M27

163 → tooth count
S8M → tooth profile / pitch family
27 → width in millimeters

The pitch length can then be calculated:

163 × 8 mm = 1,304 mm

This corresponds to the documented 1,304 mm pitch length for 163S8M27.

But this does not mean every timing belt manufacturer uses exactly the same numbering convention.

Some manufacturers may use:

• Tooth count + profile + width
• Product family + application number
• OEM-derived part numbers
• Brand-specific replacement numbers
• Numbers that omit certain technical dimensions

Therefore, the correct rule is:

Interpret the code according to the manufacturer’s numbering system, then verify the actual belt dimensions and application.

This distinction is particularly important when buying automotive timing belts in bulk.

Once you understand what a timing belt number means, the next step is to verify which replacement references correspond to the original part number. See our guide to timing belt OEM part number cross reference for OEM, Gates, Dayco, Continental, and application verification.

4. 10 Popular Automotive Timing Belt Numbers and Their Applications

The following 10 timing belt numbers are useful representative catalog examples for automotive aftermarket identification.

They should not be interpreted as a global sales ranking or a definitive “top 10” by worldwide volume. Their value is that they demonstrate different combinations of tooth count, profile, width, OEM references, and vehicle applications.

5. How to Read 163S8M27 Step by Step

Among automotive timing belt numbers, 163S8M27 is an especially useful example because the technical information is relatively clear.

5.1 What Does 163 Mean?

The first number:

163

indicates the belt has:

163 teeth

This is one of the most important dimensions in a synchronous drive because tooth count directly affects pitch length when the pitch is known.

5.2 What Does S8M Mean?

S8M identifies the timing belt tooth profile family.

The 8M portion indicates an 8 mm tooth pitch.

Pitch means the center-to-center distance between corresponding points on adjacent teeth.

Therefore:

163 teeth × 8 mm pitch = 1,304 mm pitch length

The documented specification for 163S8M27 is 1,304 mm length, 27 mm width, 8 mm pitch, and 163 teeth.

5.3 What Does 27 Mean?

The final:

27

indicates the nominal belt width:

27 mm

Therefore:

163S8M27

can be interpreted as:

163 teeth / S8M 8 mm pitch / 27 mm width

This is an excellent example of why timing belt numbers can provide more technical information than a simple aftermarket part number.

6. What the Other Automotive Timing Belt Codes Tell You

The same logic can be applied to other technical-style numbers, but the exact interpretation should always be checked against the manufacturer’s catalog.

138S8M23

This belt has:

• 138 teeth
• S8M profile
• 8 mm pitch
• 23 mm width
• 1,104 mm pitch length

Catalog references include Gates 5489XS and several Volkswagen/Audi OE numbers. Applications include Audi A3/A4 and Volkswagen Golf/Jetta examples.

162S8M25

This example has:

• 162 teeth
• S8M profile
• 8 mm pitch
• 25 mm width
• 1,296 mm pitch length

Cross-reference data includes Gates 5355XS, Kia 0K054-12-205 and Mazda RF01-12-205B. Applications include Kia Sportage, Mazda Bongo and Nissan Vanette.

169S8M24

This code identifies:

• 169 teeth
• S8M-type 8 mm pitch
• 24 mm width
• 1,352 mm pitch length

It is cross-referenced with Gates 5408XS and OEM references used on Chevrolet/GM applications including Epica, Evanda, Lacetti and Optra.

192S8M30

This is a 192-tooth, 8 mm pitch, 30 mm wide timing belt with a 1,536 mm pitch length.

It appears in Mazda applications including the 323, 626, MX-3, MX-6 and Xedos.

223YU27

This example demonstrates why the profile letter matters.

It has:

• 223 teeth
• YU profile
• 8 mm pitch
• 27 mm width
• 1,784 mm pitch length

It is used across multiple Subaru Forester, Impreza, Legacy and Outback applications.

174MY25

This belt has:

• 174 teeth
• MY profile
• 8 mm pitch
• 25 mm width
• 1,392 mm pitch length

Catalog applications include Toyota Altezza, Caldina and Celica.

104RU25

This example uses a different pitch family:

• 104 teeth
• RU profile
• 9.525 mm pitch
• 25 mm width
• 991 mm pitch length

The catalog cross-references it with Gates 5301XS and lists Mazda Bongo, Mitsubishi Delica Truck and Nissan Vanette applications.

163RU25

This is another RU-profile example:

• 163 teeth
• RU profile
• 9.525 mm pitch
• 25 mm width
• 1,553 mm pitch length

Applications include Hyundai H1, Porter and Galloper, as well as Mitsubishi L200, L300 and Pajero.

201S8M30

This example has:

• 201 teeth
• S8M profile
• 8 mm pitch
• 30 mm width
• 1,608 mm pitch length

Automotive catalog data lists the Mazda Eunos 800 2.3L as an application example.

7. Why Tooth Count Matters in Timing Belt Identification

Tooth count is one of the fastest ways to distinguish timing belts that look similar.

For an 8 mm pitch belt:

• 160 teeth = 1,280 mm pitch length
• 161 teeth = 1,288 mm pitch length
• 162 teeth = 1,296 mm pitch length
• 163 teeth = 1,304 mm pitch length
• 164 teeth = 1,312 mm pitch length

A difference of only one tooth changes the pitch length by 8 mm.

That is why a belt cannot be selected simply because its overall appearance seems similar.

For distributors, this is particularly important when several adjacent sizes are listed in the same product family.

If you need to understand timing belt dimensions in greater detail, see the Timing Belt Size Guide.

8. Timing Belt Number Meaning: Profile and Pitch Are Critical

The profile is just as important as tooth count.

Common timing belt families may include:

• S8M
• S5M
• S14M
• T5
• T10
• T20
• HTD profiles
• Automotive-specific profiles

The important point is that the same nominal pitch does not automatically mean the same tooth geometry.

For example:

8M and another 8 mm pitch belt

may share the same pitch distance while using different tooth geometry or application standards.

The tooth profile must match the pulley.

This is one reason timing belt identification should not be based on tooth count alone.

For a deeper comparison of timing belt profile families, see Timing Belt Types.

9. Automotive Timing Belt Codes vs Industrial Timing Belt Codes

Automotive and industrial timing belts can use similar-looking numerical systems, but their identification logic is not always identical.

Automotive timing belts

Automotive replacement identification often combines:

Vehicle application + OEM number + aftermarket number + technical dimensions

For example:

Toyota OE → aftermarket reference → 163S8M27

The vehicle or engine application is therefore extremely important.

Industrial timing belts

Industrial synchronous belts are more commonly identified through technical dimensions such as:

• Profile
• Pitch
• Tooth count
• Width
• Pitch length

Examples include:

5M
8M
14M
T5
T10

An industrial code may therefore provide a more direct description of the belt geometry.

For industrial buyers, the correct specification should be confirmed against the pulley and transmission design rather than selected from a visual comparison.

REALSHOW also supplies a broader range of industrial belts for industrial power-transmission applications.

10. Why Similar Timing Belt Numbers Are Not Automatically Interchangeable

This is one of the most important rules when reading timing belt numbers.

Consider two belts:

• 163S8M27
• 163RU25

Both contain 163.

But they are not equivalent.

163S8M27

• 163 teeth
• 8 mm pitch
• S8M profile
• 27 mm width
• 1,304 mm pitch length

163RU25

• 163 teeth
• 9.525 mm pitch
• RU profile
• 25 mm width
• 1,553 mm pitch length

The identical tooth count does not make them interchangeable.

This demonstrates why the identification sequence should be:

Profile → pitch → tooth count → width → application

rather than:

Tooth count only

11. How to Verify a Timing Belt Number Before Ordering

For distributors and wholesalers, a timing belt number should be verified through several independent data points.

Step 1: Read the Belt Marking

Record every visible marking.

Do not copy only the largest number.

Look for:

• Full belt code
• Manufacturer
• OEM reference
• Product series
• Width indication
• Additional suffixes

Step 2: Identify the Vehicle or Machine

For automotive applications, record:

• Vehicle brand
• Model
• Model year
• Engine displacement
• Engine code
• VIN when available

A belt number without application information may not be enough for final confirmation.

Step 3: Check the OEM Number

The OEM number is often one of the strongest references for automotive replacement identification.

For example, 163S8M27 is cross-referenced with multiple Toyota OE numbers, while 138S8M23 is cross-referenced with Volkswagen/Audi references.

Step 4: Confirm the Technical Dimensions

Check:

• Tooth profile
• Pitch
• Tooth count
• Width
• Pitch length

If one dimension conflicts with the original specification, stop the identification process and investigate further.

Step 5: Check Multiple Cross-References

A professional cross-reference should connect:

OEM → aftermarket brand → technical number → application

Do not rely on one online listing when ordering a large quantity.

Step 6: Confirm With the Manufacturer

For B2B orders, provide the supplier with as much information as possible:

• Existing belt number
• Photos
• Dimensions
• OEM number
• Vehicle/application
• Required quantity

REALSHOW’s automotive belt manufacturing service supports identification using belt markings, product dimensions, vehicle information, existing samples, and application requirements. See the Automotive Belt Manufacturer page for the broader technical support and product range.

12. Timing Belt Number Cross-Reference for Distributors

For aftermarket distributors, timing belt number identification is more than a technical exercise.

A single vehicle application can generate multiple references across different suppliers.

A practical cross-reference structure is:

Vehicle / Engine

↓

OEM Number

↓

Original Belt Specification

↓

Technical Timing Belt Code

↓

Aftermarket Brand Number

↓

Supplier Part Number

This structure makes product catalogs easier to manage.

It also helps distributors reduce:

• Wrong-order rates
• Returns
• Application errors
• Customer complaints
• Duplicate SKUs

For companies building a complete automotive belt catalog, the Automotive Belt Guide can be used as the broader reference point.

13. Common Timing Belt Number Identification Mistakes

Mistake 1: Matching only the number of teeth

Two belts can have the same tooth count but different pitches and profiles.

Solution: Always confirm profile and pitch.

Mistake 2: Treating an OEM number as a technical size

An OEM number identifies an application/reference.

It does not necessarily tell you the tooth count, pitch, and width directly.

Solution: Cross-reference the OEM number to the actual belt specification.

Mistake 3: Assuming the final number always means width

Many technical codes use the final number to indicate width, but numbering conventions vary.

Solution: Confirm the manufacturer’s catalog convention.

Mistake 4: Assuming 8M means every 8 mm pitch belt is interchangeable

Pitch alone is not enough.

Solution: Confirm the complete tooth profile and pulley compatibility.

Mistake 5: Selecting a replacement by appearance

A belt can look almost identical while having a different pitch, width, or tooth geometry.

Solution: Use measurable specifications and application data.

Mistake 6: Using only one cross-reference source

Different catalogs may contain incomplete or outdated application information.

Solution: Verify the OEM number, vehicle application, technical dimensions, and supplier data together.

14. What If the Timing Belt Number Is Missing?

Sometimes the printed marking is worn, damaged, or unavailable.

In that situation, identification can still be approached systematically.

Measure or establish:

1. Number of teeth
2. Tooth pitch
3. Belt width
4. Approximate pitch length
5. Tooth profile
6. Vehicle or machine application
7. OEM number if available

For automotive belts, application information can significantly narrow the possibilities.

For industrial belts, the combination of profile + pitch + tooth count + width is often more useful.

The key is to avoid identifying the belt from only one measurement.

15. Timing Belt Number Meaning for B2B Buyers

For distributors, importers, wholesalers, and aftermarket suppliers, timing belt numbers are also a catalog-management tool.

A strong product database should ideally connect:

This structure makes it easier for buyers to search by either:

• Belt number
• OEM number
• Vehicle
• Engine
• Aftermarket reference
• Technical specification

For distributors building a broader aftermarket belt program, OEM vs Aftermarket Automotive Belts explains the difference between original-equipment references and aftermarket supply.

16. Timing Belt Number Meaning and Manufacturer Verification

A timing belt number tells only part of the story.

Two manufacturers may produce belts with the same nominal dimensions while differing in:

• Rubber compound
• Tensile cord
• Tooth fabric
• Manufacturing consistency
• Dimensional tolerance
• Quality control
• Application coverage

Therefore, a distributor should evaluate both:

Specification accuracy

and

Manufacturing capability

When sourcing from China, buyers can also review Automotive Timing Belt Manufacturing to understand the production side of timing belt supply.

For OEM or private-label programs, the OEM Automotive Belt Manufacturer page provides additional information about specification analysis, sample evaluation, material selection, production development, and quality verification.

17. How Timing Belt Number Meaning Connects With Other Automotive Belt Numbers

Timing belts are only one part of an automotive belt system.

Other belt types use their own numbering conventions.

For example:

PK Belt

A number such as:

4PK850

is typically interpreted around:

• 4 ribs
• PK profile
• approximately 850 mm effective length, depending on the specific numbering convention

For a detailed explanation, see PK Belt Number Meaning.

V-Belt

V-belts may use designations such as:

• A
• B
• C
• 3V
• 5V
• 8V

The identification logic is different from automotive timing belts.

See How to Identify a V-Belt for the corresponding identification process.

This distinction matters when building a multi-category automotive belt catalog.

18. Automotive Timing Belt Identification Checklist

Before confirming a timing belt replacement or wholesale order, check:

• Full belt marking recorded
• Tooth count confirmed
• Tooth profile confirmed
• Pitch confirmed
• Belt width confirmed
• Pitch length confirmed
• OEM number checked
• Vehicle/application confirmed
• Engine code checked where applicable
• Aftermarket cross-reference verified
• Manufacturer numbering convention confirmed
• Supplier specification sheet reviewed
• Sample or drawing checked for uncertain applications

For B2B sourcing, this checklist can prevent many avoidable application errors.

19. FAQ: Timing Belt Number Meaning

What does a timing belt number mean?

A timing belt number may identify the belt’s tooth count, pitch, profile, width, product series, or manufacturer-specific part reference. The exact meaning depends on the numbering system.

How do I read 163S8M27?

163S8M27 can be interpreted as 163 teeth, S8M profile with 8 mm pitch, and 27 mm width. Its pitch length is 1,304 mm.

Does 163 mean 163 teeth?

In a technical code such as 163S8M27, the 163 represents the tooth count. However, buyers should confirm the manufacturer’s catalog before assuming the same rule applies to every belt number.

What does 8M mean on a timing belt?

8M generally identifies an 8 mm pitch timing belt family. The exact tooth geometry and application should still be confirmed before replacement.

Are timing belt numbers standardized?

No. Different manufacturers and belt families can use different numbering conventions.

Can two timing belts with the same tooth count replace each other?

Not necessarily. Pitch, tooth profile, width, pitch length, and application must also match.

What is the difference between an OEM number and a timing belt code?

An OEM number primarily identifies the original vehicle or engine application. A technical timing belt code may describe the belt’s dimensions and profile.

How can I identify a timing belt without a part number?

Measure the tooth count, pitch, width, and profile, then combine those measurements with vehicle or machine application information and OEM references.

What information should I send a manufacturer for timing belt identification?

Provide the existing belt number, photos, dimensions, OEM number if available, vehicle or machine application, and required quantity. A sample belt can also help with verification.

20. Final Takeaway: Timing Belt Number Meaning

The most important point is simple:

A timing belt number should be interpreted as a complete identification system, not as a single number.

For automotive timing belts, reliable identification combines:

Number → Profile → Pitch → Teeth → Width → OEM → Application → Cross-reference

The example 163S8M27 demonstrates how a technical timing belt code can provide useful dimensional information:

163 teeth + S8M + 8 mm pitch + 27 mm width = 1,304 mm pitch length

But the same approach should not be applied blindly to every manufacturer’s numbering system.

For distributors, importers, wholesalers, and aftermarket buyers, the safest method is to combine belt marking, OEM reference, vehicle/application information, technical dimensions, and manufacturer cross-reference data before confirming an order.

For buyers sourcing automotive timing belts and other automotive belt products, the REALSHOW automotive timing belt category provides the relevant product direction, while the Automotive Belt Manufacturer page explains REALSHOW’s broader manufacturing and aftermarket supply capability.

Contact Realshow Team today!