RC Bearing Sizes Explained: What to Check Before You Buy

Before buying RC bearings, match the inside diameter, outside diameter and width to your vehicle’s manual. Then confirm the bearing type, part number and location. A matching measurement is a useful check, but it does not prove that a bearing or kit fits your vehicle.

This guide from J-M SUPPLIES RC Parts Store explains how to read those details and build a clear order list. Start with the exact model and version, especially if the vehicle has replacement hubs, axles or other upgrades.

What the three bearing measurements mean

A metric ball-bearing size is often written as three numbers, such as 5 × 11 × 4 mm. Read the listing’s labels to confirm their order:

• Inside diameter: the distance across the center hole. It may be called the bore or marked d.
• Outside diameter: the distance across the outside of the bearing. It may be marked D.
• Width: the thickness from one flat face to the other. It may be marked B.

In that example, the hole is 5 mm across, the outside is 11 mm across and the bearing is 4 mm wide. These are bearing dimensions, not the vehicle’s scale or wheel size. Bearing maker NSK uses d, D and B for these dimensions; its example product is a terminology reference, not a recommendation for your RC.

Find the part in your exact vehicle’s manual

Use the parts list and exploded drawing—a diagram showing the separate parts and where they belong. Record the bearing’s original part number, size, location and the quantity required for your repair.

For example, the Tekno SCT410 2.0 manual’s bearing list includes 5 × 11 × 4 and 6 × 10 × 3 bearings, as well as a separately identified flanged bearing. This shows why one size should not be assumed to cover a whole vehicle. It does not establish that any particular J-M SUPPLIES RC Parts Store kit fits that model.

Keep the part number beside the dimensions. A packet quantity is not necessarily the number used in the assembly you are repairing.

Use measurement to check, rather than guess

If you already have the removed part, a caliper—a measuring tool with sliding jaws—can help you compare its dimensions with the manual. Check the center hole, outside and width, and record the units. Follow the vehicle’s instructions for safe access and removal.

Do not round a reading to the nearest familiar size or choose a bearing because it looks similar. If the measurement and manual disagree, check the model version and any changed components before ordering. A worn or damaged part is not a substitute for the manufacturer’s specification.

Size is only part of the match

Also check whether the original part has a special shape or function. A flanged bearing has a raised rim; do not treat it as the same part as a plain bearing simply because some dimensions match.

Check the specified bearing cover or seal type, too. Keep that choice separate from the size check. Our RC product FAQs explain the rubber-shielded and metal-shielded bearing-kit options offered by J-M SUPPLIES RC Parts Store. Confirm the exact listing’s coverage and exclusions, particularly for a modified vehicle.

Make a short bearing order list

• Exact vehicle model number and version.
• Assembly or location where the bearing belongs.
• Original part number and manual reference.
• Inside diameter, outside diameter, width and units.
• Required bearing type and quantity.
• Any upgrade or mismatch that still needs confirmation.

For a larger repair, use our RC rebuild checklist to keep bearings, screw hardware and other parts organized. Compare your confirmed needs with the exact kit listing; a larger piece count is not proof of better coverage.

When does a model-specific bearing kit make sense?

If your repair list includes bearings for several confirmed locations, a model-specific kit gives you one set to compare with that list. It can be a convenient option instead of finding each replacement size separately.

At J-M SUPPLIES RC Parts Store, start with your exact RC model, then review the rubber-shielded or metal-shielded bearing-kit options shown for it. Compare the selected kit’s contents and coverage with the work you plan to do. Check any modified parts separately, and ask before ordering if a needed bearing is not clearly covered.

For one bearing, an individual replacement may be enough. Consider a kit when its confirmed coverage suits your repair or rebuild; buying a set does not mean you need to replace every bearing on the vehicle.

Common RC bearing size questions

Does 5 × 11 × 4 fit every RC car?

No. It describes dimensions, not a vehicle application. Match the exact vehicle, assembly, original part reference and bearing type.

Can two bearings with the same hole size be different?

Yes. The outside diameter, width or design can differ. Check all required details instead of matching only the first number.

What if I cannot confirm the size or part number?

Keep it marked as uncertain. Send your model details, assembly location and clear photos through our RC model help form before ordering a substitute.