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When a worn or undersized bearing causes wobble, noise, or premature failure in a compact mechanism, finding the exact inch-dimension replacement quickly matters. Hobbyists, RC builders, and maintenance technicians working with inch-standard equipment rely on R-series ZZ miniature deep groove ball bearings to restore smooth, low-friction rotation without adapting to metric alternatives.
These miniature deep groove ball bearings are manufactured to inch dimensions across 15 standard R-series models — from R2 (3.175 × 9.525 × 3.967 mm / 0.125" × 0.375" × 0.156") up to R22 (34.925 × 63.5 × 14.288 mm / 1.375" × 2.500" × 0.563") — plus compact fractional sizes R144, R166, R168, and R188. Each bearing features dual pressed-steel shields (ZZ) that retain grease and exclude light contaminants without contact friction.
Typical use cases include RC car and drone drivetrains requiring inch-bore miniature ball bearings, skateboard and inline skate wheel hubs using R-series ZZ replacements, small electric motor and spindle rebuilds, and precision hobby machinery such as lathes and milling attachments where inch-standard deep groove ball bearings are specified.
| Bearing Type | Deep Groove Ball Bearing |
|---|---|
| Dimension Standard | Inch (Imperial) |
| Shield Type | ZZ (Dual Pressed-Steel, Non-Contact) |
| Available Models | R2, R3, R4, R6, R8, R10, R14, R16, R18, R20, R22, R144, R166, R168, R188 |
| Bore Diameter (d) Range | 3.175 mm – 34.925 mm (1/8" – 1-3/8") |
| Outer Diameter (D) Range | 6.35 mm – 63.5 mm (1/4" – 2-1/2") |
| Width (B) Range | 2.779 mm – 14.288 mm (0.109" – 0.563") |
| Lubrication | Grease-packed (factory fill) |
| Load Direction | Radial + Moderate Axial (both directions) |
| Pack Quantities | 1 / 3 / 5 / 10 pcs |
| Exact Dimensions per Model | See variant options |
| Dynamic Load Rating | See variant options |
| Static Load Rating | See variant options |
| Max RPM | See variant options |
Measure three dimensions on your existing bearing or housing: bore diameter (d), outer diameter (D), and width (B). Match these to the model listed in the variant name — for example, R8-ZZ is 12.7 × 28.575 × 7.938 mm. If you only have the model number stamped on the old bearing, select the matching variant directly. When in doubt, contact us to confirm before ordering.
ZZ bearings use pressed-steel shields that sit close to the inner ring without touching it. This non-contact design produces very low friction and allows higher operating speeds. 2RS bearings use rubber contact seals that provide better contamination exclusion but generate more drag. ZZ is the better choice for high-speed motors, RC drivetrains, and spindles; 2RS suits slower applications in wet or dusty environments.
Yes, to a moderate degree. Deep groove ball bearings support radial loads as their primary function and can accommodate axial loads in both directions up to roughly 20–30% of their dynamic radial load rating. For applications where axial load is the dominant force, a dedicated thrust bearing is more appropriate.
ZZ steel shields provide basic protection against dust and light splash, but they are not waterproof. For outdoor or wet environments, consider applying a compatible bearing grease after installation or look for 2RS rubber-sealed variants. Avoid prolonged submersion or direct water spray on ZZ-shielded bearings.
Order a 1-piece pack for a single repair or to verify fitment before committing to more. Choose 3 or 5 pcs if you are servicing multiple units at once or want to keep spares on hand. The 10-piece pack offers the lowest per-unit cost and is suited for workshop stock, fleet maintenance, or production use. Note that not all models are available in the 10-piece option — check the variant selector for availability.
The R-number is an ABEC/AFBMA inch-series designation. The number loosely corresponds to the bore diameter in units of 1/16 inch — for example, R8 has a bore of 8/16" = 1/2" = 12.7 mm. Fractional models like R144 (1/4 × 4 = 1/4" bore, 4/16" OD) follow a two-digit sub-series convention. Always verify against the exact d × D × B dimensions listed in the variant name rather than relying solely on the model number formula.
ZZ shields can be carefully pried off with a thin tool for cleaning and re-greasing, unlike rubber 2RS seals which are more difficult to remove without damage. Use a light bearing grease (NLGI Grade 2 is common) and avoid over-packing, which increases drag and heat. Re-seat the shield firmly before reinstalling the bearing.
