How to Determine if a Trailer Wheel is Hub-centeric or Lug-centric

Question:

We have a late 70s vintage but hardly used COX boat trailer with 4.80-8 tires and wheels original which are the tires are cracked. We anticipate using the trailer more and wish to upgrade to 4.80-12. We have enough clearance all around. The issue is if the wheels are hub or lug centric? The wheels are attached via lug bolts not nuts that are conical not flat where they meet the wheel. However, the wheel also sits very snug on the hub. So I cant determine if a wheel with a larger hub bore would be acceptable and safe. Are there other clues to figure out if the wheel is hub or lug centric?. If the bolts are conical does it matter from a load perspective? You help is much appreciated.

asked by: Steve B

Expert Reply:

The wheels are hub-centric. The wheel bolts instead of lug nuts is the only clue needed. A hub-centric wheel centers on the hub using the pilot hole and hub so it would be a snug fit. You could still use a lug-centric wheel as long as the pilot hole of the new wheel is exactly the same as the old wheels.

To determine if any of the 4.80-12 tire and wheel combos we have will fit I will need to know the bolt pattern of the wheels and the diameter of the pilot hole. I have linked a help article that explains how to measure for bolt pattern.

If none end up fitting then you would also have to replace the hubs. To do this I would need to know the inner and outer bearing numbers stamped into the bearings. Or I would need to know some specific measurements shown in the picture I have provided. In the picture, B, C, and D are the most important.

The measurements, including the pilot hole for the wheel, need to be as accurate as possible so you will need dial or digital calipers to take the measurements.

expert reply by: Michael H