How to Determine the Size of a Trailer Hub Assembly for Replacement

Expert Reply:

To determine the size of the hub assembly you need to purchase you have to determine which bearings are in the old assembly. If the old assembly has L44649 inner bearings, you would use the hub you chose # 8-258-5UC1. If the inner bearings are marked L44643, you will need # 8-258BTUC1. If you do not have the old bearings, you need to measure the inner bearing surface on the spindle to determine if the 1.063 inch dimension or 1.00 inch dimension will be needed to accept the bearing. You can also measure the inner seal mounting surface and those dimensions would be 1.5 inches and 1.249 inches respectively. I have provided links for these two products and this will help with dimensions and pictures. Remember to make sure the bolt pattern is the same. You can use the measurement guide for this at the bottom of either hub assembly page.

Here are the specific measurements for each hub.

Hub 8-258-5UC1
bearing # L44649
Inner bearing dimension is 1.063 inches
Inner seal dimension is 1.500 inches


Hub 8-258BTUC1
bearing #L44643
Inner bearing dimension is 1.00 inches
Inner seal dimension is 1.249 inches

expert reply by: Bob G