# What is 1308 PCD? A Complete Guide to Pitch Circle Diameter
**Pitch Circle Diameter (PCD)** is a fundamental measurement in engineering and manufacturing, crucial for the proper fit and function of wheels, gears, and other circular components. If you’re dealing with machinery, automotive parts, or industrial equipment, understanding PCD is non-negotiable. This guide provides a complete breakdown, focusing specifically on the **1308 PCD** specification.
## **Understanding Pitch Circle Diameter (PCD)**
PCD refers to the diameter of an imaginary circle that passes through the center of all the bolt holes or studs on a mounting hub. It is the key measurement that ensures multiple fasteners are spaced correctly to match the corresponding hub. An incorrect PCD means the component simply will not fit.
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What Does 1308 PCD Mean?
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The term “1308 PCD” specifies a Pitch Circle Diameter of **130.8 millimeters**. This is a common measurement found in various industrial applications, particularly in heavy machinery, large bearings, and specific automotive or truck wheel configurations. The “1308” is simply the metric measurement expressed in millimeters (often written as 130.8 or 5-1/8 inches in imperial).
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Key Applications and Industries
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The 1308 PCD is frequently encountered in sectors requiring robust and precise components. Its primary applications include:
* **Heavy-Duty Vehicle Hubs:** Certain truck, trailer, and bus wheel hubs.
* **Industrial Machinery:** Large gear assemblies, flywheels, and rotating equipment bases.
* **Agricultural Equipment:** Tractors and harvesters where high torque and load are factors.
* **Specialized Cutting Tools:** For example, it can be relevant in the mounting of large PDC (Polycrystalline Diamond Compact) cutter blocks used in drilling and mining. You can explore high-performance 1308 PCD cutter solutions for demanding applications.
## **How to Measure 1308 PCD Accurately**
For a 4-bolt pattern, measuring PCD is straightforward: simply measure the distance between the centers of two opposite bolt holes. For patterns with 5, 6, or 8 bolts, the process involves more complex geometry. Using a precision **PCD gauge** or calculating using bolt circle formulas is recommended for accuracy. Always verify specifications with manufacturer data sheets when possible.
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Common Questions About 1308 PCD
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Can I use a wheel with a different PCD?
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No. The PCD must match exactly. Using adapters (PCD converters) is possible but not recommended for high-stress applications as they can introduce weakness and safety risks.
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Is 130.8mm PCD the same as 5-1/8″?
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Essentially, yes. 130.8mm converts to approximately 5.15 inches, often rounded and referred to as a 5-1/8 inch bolt circle in imperial measurements. Always confirm the exact measurement.
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Where can I find components with a 1308 PCD?
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Specialist industrial suppliers, heavy vehicle parts distributors, and manufacturers of large-bore components are your best sources. Ensure you provide the full specification including number of bolts and thread size.
## **Ensure Perfect Fit and Performance**
Understanding and correctly applying the **1308 PCD** measurement is critical for safety, performance, and avoiding costly installation errors. Whether you’re replacing a wheel hub or specifying a component for a machine, double-checking the PCD is