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except to say that being made to a minimum standard isn't always the same as being made to a specification
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The standard IS the specification. If you are choosing a bearing, there are various classifications that determine the clearances and subsequent precision for a given class. Generally wheel bearings are a very low class (high clearance) bearing. You can get bearings that are a higher class (lower clearance higher precision) bearings for cheaper than you can buy the lower class bearings from the dealership.
We probably use the same bearings that are in your front wheel on one of our conveyors in the plant. Bearings are not designed for specific applications... i.e. motorcycle wheel, they are designed for certain conditions and loads... i.e. low rpm, dirty environment with a peak radial load of x and a peak axial load of y.
Want to learn more:
SKF website
Surf a little and you can learn all you want about bearings.
The bearings in your wheels are VERY low quality as far as industry standards go. They don't have to be capable of high accuracy or able to withstand high rpm's.
We have high speed spindle bearings in CBN grinding applications that are capable of running continuously at 35,000 to 40,000 rpm with zero failures for 3-4 years. In comparison a motorcyce bearing in comparision turns approx. 194 rpm at 70 MPH...
If they drove them out of the wheel from the inner race (which they had to do to get them out), I'd replace them...if you don't you probably will in about 5k miles. Pay me now or pay me later. It's not a safety issue or anything...the bike won't come apart if you use the old bearings (for a while).