30209 Bearing Dimensions: 45x85x20.75mm Tapered Roller

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Reviewed by MLC Editorial Team | 16 August 2026

Verified by Rachel Mayfield, Supply Chain Analyst - August 2026

The 30209 is a single-row tapered roller bearing with a 45 mm bore, 85 mm outside diameter and 20.75 mm overall width. The dimensions come from ISO 355 and DIN 720, so a 30209 from SKF, FAG, Timken, NSK, NTN or Koyo is dimensionally interchangeable. Unlike a ball bearing, the 30209 is separable: the cone (inner ring with rollers and cage) and the cup (outer ring) come apart and are fitted separately.

30209 bearing dimensions

Property	Value	Standard
Bore diameter (d)	45 mm	ISO 355 / DIN 720
Outside diameter (D)	85 mm	ISO 355 / DIN 720
Overall width (T)	20.75 mm	ISO 355 / DIN 720
Cone (inner ring) width (B)	19 mm	ISO 355 / DIN 720
Cup (outer ring) width (C)	16 mm	ISO 355 / DIN 720
Bearing type	Single-row tapered roller bearing	ISO 355

T, B and C: three widths, commonly confused

Tapered roller listings quote three widths and mixing them up leads to wrong orders. T is the overall assembled width of the 30209 - 20.75 mm - and is the figure that matters for the stack-up in a hub or gearbox. B is the cone width (19 mm) and C is the cup width (16 mm). Because the rings are offset when assembled, B and C are both smaller than T and they do not add up to it. When a listing quotes a single width for a 30209, check it is 20.75 mm - a listing showing 19 mm is quoting the cone only.

Cone and cup: fitted separately, replaced together

The cup presses into the housing and the cone assembly slides or presses onto the shaft. That separability is what makes tapered rollers convenient in wheel hubs - each part is drifted in on its own. Replace cup and cone as a set even though they are sold separately in some trade counters: running a new cone against a worn cup transfers the old wear pattern straight into the new part.

Adjustment: tapered rollers are set, not just fitted

A single tapered roller bearing cannot control a shaft on its own - it only takes axial load in one direction. The 30209 is almost always mounted opposed to a second tapered bearing, and the pair is adjusted at assembly: the clamping nut or shim pack sets the running clearance (end float) or preload. A classic trailer-hub setting is to tighten the axle nut while rotating the hub until it just binds, then back off to the first split-pin slot. Gearbox and pinion applications use a measured preload instead - follow the equipment maker's figure, not a generic one.

Brand interchange for the 30209

The 30209 number is used unchanged by every major maker: SKF, FAG (Schaeffler), NSK, NTN, Koyo and Timken's metric range all supply a 30209 with identical boundary dimensions. The one trap is Timken's imperial ranges - designations such as LM11949/LM11910 are inch-series bearings with their own dimensions and do NOT interchange with the metric 30209 even where the sizes look close. Match the full designation, then check 45x85x20.75 mm.

Load ratings: check the maker's catalogue

Dynamic and static load ratings for the 30209 differ between manufacturers and ranges, so MLC does not publish a single figure. SKF, Schaeffler medias, Timken, NSK and NTN all publish free catalogues with per-variant ratings, limiting speeds and the axial load factors that matter for tapered rollers.

Where the 30209 is used

Tapered rollers carry combined radial and axial load, which is why they own the wheel-hub and gearbox world. Typical 30209 applications include light commercial axles, gearboxes and agricultural equipment.

References

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Frequently Asked Questions

What size is a 30209 bearing?

A 30209 tapered roller bearing measures 45 mm bore x 85 mm outside diameter x 20.75 mm overall width (T). The cone width (B) is 19 mm and the cup width (C) is 16 mm. Dimensions are set by ISO 355 / DIN 720 and are the same for every manufacturer.

Can I replace just the cone or just the cup of a 30209?

The parts separate and are sold separately, but replace them as a pair. A new cone run against a worn cup inherits the old wear pattern and fails early. The only routine exception is initial assembly, where cup and cone are fitted to housing and shaft independently.

What is the difference between the 30209 and a ball bearing of the same bore?

The 30209's tapered rollers carry heavy radial load and axial load in one direction at the same time, and the bearing is separable and adjustable. A deep groove ball bearing of the same bore is quieter, faster and needs no adjustment, but carries far less combined load. Wheel hubs and gearboxes use tapered rollers; motors and general machinery use ball bearings.

Does a 30209 need preload?

It needs setting, one way or the other. Tapered roller pairs are adjusted at assembly to either a small running clearance (end float) or a preload, depending on the application. Wheel hubs are typically set to a just-free end float; gearbox pinions run measured preload. Use the equipment manufacturer's setting.

Independent UK engineering trade publication. Company profiles cross-referenced with Companies House.

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