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wheelchair bearing guide

Wheelchair bearings may be small, but they play an important role in how smoothly your wheelchair rolls. Bearings are commonly used in rear wheels, caster wheels, and other moving components, and the correct size is essential for proper fit and performance.

Because bearing sizes can vary by wheelchair brand, model, year, wheel, and caster configuration, it is always best to measure the bearing you are replacing rather than relying only on the wheelchair manufacturer or model.

What You’ll Learn in This Guide

This guide covers:

  • Common rear wheel and caster bearing sizes
  • Bearing dimensions and measurement basics
  • How to read common bearing codes
  • The difference between ID, OD, and width
  • Common seal and shield markings such as 2RS, ZZ, and 2Z
  • Examples of bearing sizes commonly found on popular wheelchair brands

Why Bearing Size Matters

A bearing that looks nearly identical to your original may still be the wrong size. Even small differences in inside diameter, outside diameter, or width can prevent the bearing from fitting correctly.

The inside diameter (ID) must properly fit the axle or mounting hardware, while the outside diameter (OD) must fit the wheel or hub. The bearing width (W) also affects how the bearing sits inside the component.

This is especially important when comparing measurements such as 12 mm and 1/2 inch. Although they may appear close in size, they are not interchangeable.

Rear Wheel Bearings vs. Caster Bearings

Rear wheel bearings and caster bearings are measured the same way, but they are often different sizes.

Rear wheels commonly use larger bearings designed around the wheelchair axle, while caster wheels frequently use smaller metric bearings. The exact bearing can still vary depending on the wheel, caster, fork, and manufacturer.

For that reason, the safest approach is always to check the bearing code when available and confirm the measurements before ordering.

How to Identify Your Bearing

If the bearing is accessible, first check the seal or shield for a printed code such as:

R8, R6, 608, 2RS, ZZ, or 2Z

If no code is visible, measure:

ID — Inside Diameter
The opening through the center of the bearing.

OD — Outside Diameter
The full outside diameter of the bearing.

W — Width
The thickness of the bearing from side to side.

For the most accurate measurement, we recommend using a caliper rather than a standard ruler.

What Do 2RS, ZZ, and 2Z Mean?

These markings describe how the bearing is protected.

2RS bearings have rubber seals on both sides. These seals help protect the internal bearing components from dirt and moisture.

ZZ / 2Z bearings use metal shields on both sides. These shields help protect the bearing from dust and debris while typically creating less contact than rubber seals.

When replacing a bearing, it is best to match both the bearing size and the seal or shield style whenever possible.

Before Ordering Replacement Bearings

Before purchasing a replacement, verify:

  • Bearing ID
  • Bearing OD
  • Bearing width
  • Bearing code, if available
  • Axle or mounting diameter
  • Whether the bearing is being used in a rear wheel or caster
  • Seal or shield type

Wheelchair manufacturers may use different bearing configurations across models, production years, wheels, and caster options, so a model name alone may not always be enough to identify the correct bearing.

Ready to Find the Right Bearing?

Once you have confirmed your measurements and bearing type, browse our selection of replacement wheelchair bearings in common rear wheel and caster sizes.

Shop Wheelchair Bearings → Bearings