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Determining the Correct Bearing and Grease Seal Size for Trailer


hi, i bought a used trailer which I think originally came in a box and assembled by the original owner. one of the bearings is noisy. i am not sure how to pick the bearing kit or the seal. the inner and outer bearings are almost the same but apparently have slightly different inner diameter. oreily sold me 2 national 30502 or 30205 but this means inner and outer are the same and they are not. the seal also didnt work. so i ended up returning. please let me know what specs you need to identify the kit.


Expert Reply:

If you have the old bearings and seals, it is possible to find the part numbers stamped into them. If these do not have numbers or if they have worn off over time, you will need to take some measurements.

I recommend using a digital caliper like the # PTW80157 4" Carbon Fiber Digital Caliper to take measurements. If you take the inner and outer diameter measurements you will be able to find the correct replacements.

I have attached a picture showing the measurements as well as a helpful article with a sizing chart for common bearing sizes that you may reference.

How to Determine Correct Bearings, Races and Grease Seals.
How to Determine Correct Bearings, Races and Grease Seals.
(click to enlarge)
expert reply by:
Robin H

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