I believe they are milled for s13 bearings. After my ebay bearings turned out to be totally wrong (shouldn't have ordered them, they were advertised as being for 89-98...red flag right there), I pressed the bearings out of my stock hubs and pressed them into the Ichibas. One side worked fine, the other not so much, and I'm attributing that to the inferior material of the Ichiba hub. The bearing housing wore down when the bearing started vibrating. There was basically no force required to press the bearing in, it just fell into place once it was halfway in.Hijacker wrote:My only concern with trying to press OE bearings into ichiba hubs is that they might not be milled to factory spec. I'm not sure if they use custom bearings to press an S14 5 lug inner hub to an S13 outer bearing race or what. If something similar to that is the case, there isn't an OE hub you can buy that would work as there are minute differences between S13 and S14 bearings.