# Needle roller bearing inner rings IR and LRT (IR 12x15x16, IR 20x25x26.5, LRT 5812): bore d, raceway diameter F, width B

> What are the dimensions of an IR 12x15x16 or IR 20x25x20.5 needle bearing inner ring: bore, raceway diameter F and width?

- Category: Hardware › Bearings, rails & motion
- Kind: Standard part
- Basis: SKF IR designations from the Acorn parts list and Koyo LRT rows, cross-checked on IR 5x8x12 = LRT 5812; numbers only (no chamfer r min published in the lists read)
- Page: https://xemstudio.com/objects/needle-roller-bearing-inner-rings-ir-lrt/ · JSON: https://xemstudio.com/api/geometry?object=needle-roller-bearing-inner-rings-ir-lrt · Plain text: https://xemstudio.com/objects/needle-roller-bearing-inner-rings-ir-lrt/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files CC BY 4.0 or their publisher's license
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**Exact dimensions.** True size, with no tolerance added.

## Notes

- An IR (SKF, INA) or LRT (Koyo, IKO) ring is the hardened inner ring that goes with an NK or RNA needle bearing when the shaft itself is not hardened and ground. The bearing designation IR d x F x B reads bore, raceway diameter, width; F equals the Fw of the bearing it pairs with (an IR 12x15x16 runs with a bearing of Fw 15).
- Numbers: the SKF IR designations as listed on the Acorn Industrial Services parts list (the designation itself carries d, F and B) and the first LRT rows of Koyo's inner-ring table (d, F, B in separate columns). IR 5x8x12 and LRT 5812 are the same size in the two makers. Partial: this is the set of rings read, not the full catalogue. The chamfer r min of the rings is not in the lists read, so there are no files.
- Left out: the full IR range (Acorn lists 143 SKF rings in 8 pages; only the designations read are shown), the ring chamfers, oil-hole versions, LRTZ, JR / EG / ER (INA) numbers, rings above 140 mm.

## Sizes

| inner ring | bore d, mm | raceway Ø F (= bearing Fw), mm | width B, mm | an NK / RNA row with this Fw is on the NK page | source |
|---|---|---|---|---|---|
| IR 5x8x12 | 5 | 8 | 12 | yes (NK/RNA page) | SKF (Acorn listing) |
| IR 8x12x10.5 | 8 | 12 | 10.5 | yes (NK/RNA page) | SKF (Acorn listing) |
| IR 10x13x12.5 | 10 | 13 | 12.5 | — | SKF (Acorn listing) |
| IR 10x14x13 | 10 | 14 | 13 | yes (NK/RNA page) | SKF (Acorn listing) |
| IR 10x14x20 | 10 | 14 | 20 | yes (NK/RNA page) | SKF (Acorn listing) |
| IR 12x15x16 | 12 | 15 | 16 | yes (NK/RNA page) | SKF (Acorn listing) |
| IR 12x15x16.5 | 12 | 15 | 16.5 | yes (NK/RNA page) | SKF (Acorn listing) |
| IR 12x16x16 | 12 | 16 | 16 | yes (NK/RNA page) | SKF (Acorn listing) |
| IR 17x20x16 | 17 | 20 | 16 | yes (NK/RNA page) | SKF (Acorn listing) |
| IR 20x25x20.5 | 20 | 25 | 20.5 | yes (NK/RNA page) | SKF (Acorn listing) |
| IR 20x25x26.5 | 20 | 25 | 26.5 | yes (NK/RNA page) | SKF (Acorn listing) |
| IR 20x25x38.5 | 20 | 25 | 38.5 | yes (NK/RNA page) | SKF (Acorn listing) |
| IR 25x30x26.5 | 25 | 30 | 26.5 | yes (NK/RNA page) | SKF (Acorn listing) |
| IR 30x35x13 | 30 | 35 | 13 | yes (NK/RNA page) | SKF (Acorn listing) |
| IR 35x40x17 | 35 | 40 | 17 | yes (NK/RNA page) | SKF (Acorn listing) |
| IR 35x40x20 | 35 | 40 | 20 | yes (NK/RNA page) | SKF (Acorn listing) |
| IR 40x45x30 | 40 | 45 | 30 | — | SKF (Acorn listing) |
| IR 40x50x22 | 40 | 50 | 22 | — | SKF (Acorn listing) |
| IR 50x55x25 | 50 | 55 | 25 | — | SKF (Acorn listing) |
| IR 50x55x35 | 50 | 55 | 35 | — | SKF (Acorn listing) |
| IR 50x60x25 | 50 | 60 | 25 | — | SKF (Acorn listing) |
| IR 55x65x28 | 55 | 65 | 28 | — | SKF (Acorn listing) |
| IR 60x68x25 | 60 | 68 | 25 | — | SKF (Acorn listing) |
| IR 60x70x25 | 60 | 70 | 25 | — | SKF (Acorn listing) |
| IR 65x75x28 | 65 | 75 | 28 | — | SKF (Acorn listing) |
| IR 80x90x54 | 80 | 90 | 54 | — | SKF (Acorn listing) |
| IR 110x120x30 | 110 | 120 | 30 | — | SKF (Acorn listing) |
| IR 140x160x50 | 140 | 160 | 50 | — | SKF (Acorn listing) |
| LRT 5710 | 5 | 7 | 10 | yes (NK/RNA page) | Koyo (LRT) |
| LRT 5812 | 5 | 8 | 12 | yes (NK/RNA page) | Koyo (LRT) and SKF |
| LRT 5816 | 5 | 8 | 16 | yes (NK/RNA page) | Koyo (LRT) |
| LRT 6810 | 6 | 8 | 10 | yes (NK/RNA page) | Koyo (LRT) |
| LRT 6912 | 6 | 9 | 12 | yes (NK/RNA page) | Koyo (LRT) |
| LRT 6916 | 6 | 9 | 16 | yes (NK/RNA page) | Koyo (LRT) |
| LRT 61010 | 6 | 10 | 10 | yes (NK/RNA page) | Koyo (LRT) |
| LRT 7910 | 7 | 9 | 10 | yes (NK/RNA page) | Koyo (LRT) |
| LRT 71012 | 7 | 10 | 12 | yes (NK/RNA page) | Koyo (LRT) |
| LRT 71016 | 7 | 10 | 16 | yes (NK/RNA page) | Koyo (LRT) |
| LRT 81011 | 8 | 10 | 11 | yes (NK/RNA page) | Koyo (LRT) |
| LRT 91211 | 9 | 12 | 11 | yes (NK/RNA page) | Koyo (LRT) |
| LRT 91212 | 9 | 12 | 12 | yes (NK/RNA page) | Koyo (LRT) |
| LRT 91216 | 9 | 12 | 16 | yes (NK/RNA page) | Koyo (LRT) |

## Where the files are

- Acorn Industrial Services (SKF): [SKF inner rings for needle roller bearings IR d x F x B (designations as listed)](https://www.acorn-ind.co.uk/skf/bearings/roller-bearings/needle-roller-bearings/needle-roller-bearing-components) — web — Publisher's page; dimensions are facts
- Koyo (JTEKT), via AIMS Industrial: [Inner rings LRT / LRTZ for needle roller bearings: d, F, B (first rows, shaft 5 to 9 mm)](https://aimsindustrial.com.au/cdn/shop/files/IKO-Needle-Roller-Bearing-Inner-Rings-Catalogue-Pages-7-to-12-Selected.pdf) — web — Publisher's page; dimensions are facts
- McMaster-Carr: [Needle bearings (free STEP/IGES per part, for your own design use; no redistribution)](https://www.mcmaster.com/needle-bearings) — STEP, IGES, PDF — McMaster-Carr site terms: personal design use, no redistribution (verify at link)

## Questions

**What are the dimensions of an IR 12x15x16 inner ring?**

Bore 12, raceway diameter 15, width 16 mm; it runs with an NK 15/16 style bearing (Fw 15).

**What do the numbers in IR 20x25x26.5 mean?**

Bore 20 mm, raceway (F) 25 mm, width 26.5 mm.

**Is IR 5x8x12 the same as LRT 5812?**

Yes: bore 5, F 8, width 12 mm in SKF and Koyo.

**Which inner ring fits an NK 10/16 bearing?**

One with F = 10 mm, e.g. Koyo LRT 71016 (bore 7, F 10, width 16); only the rings in the table were read, so check the maker's list for other widths.

**Do I need an inner ring for an NK bearing?**

Only if the shaft is not hardened and ground to the Fw tolerance; otherwise the needles can run directly on the shaft.

## Fits with

- [Needle roller bearings NK, NKS, RNA4900 (NK10/16, NK20/20, RNA4904 and more): Fw, OD, width, r min + 14 ring-envelope STEP/STL files](https://xemstudio.com/objects/needle-roller-bearings-nk-rna-nks/)
- [HK needle roller bearings (drawn cup): HK0306 to HK2020 bore, outside diameter and width + STEP/STL envelopes](https://xemstudio.com/objects/needle-roller-bearings-hk-series/)
- [One-way clutch bearings HF series (HF0812, HF1012, HF1216, HF2016): roller-set bore Fw, OD, width, torque](https://xemstudio.com/objects/one-way-clutch-bearings-hf-series/)
- [Cylindrical roller bearings NU2xx and NU3xx (NU205, NU206, NU208, NU305, NU310 and more): bore, OD, width, r, Fw + 18 ring-envelope STEP/STL files](https://xemstudio.com/objects/cylindrical-roller-bearings-nu2xx-nu3xx/)
- [Thrust ball bearings 51100 series (51100 to 51130): bore, outside diameter, height, housing washer bore + STEP/STL envelopes](https://xemstudio.com/objects/thrust-ball-bearings-51100-series/)