How to Determine if 4-Lug Trailer Hubs can be Changed to 5-Lug Trailer Hubs

Question:

Thinking about changing the 4-lug hubs of my trailer’s axle to 5-lug hubs. Is it as easy as just swapping out? What measurements do I need to know? Thank you.

asked by: Mario T

Helpful Expert Reply:

It is possible you can just swap out a 4-lug hub with a 5-lug hub so long as you know the hub you need. And in order to determine this (if you aren't sure already), there's a number of things you'll need to know.

First, you need to know the weight rating of your axle, and also what bearings your current hub has. You will need to take apart your current hub assembly and look at the bearings themselves; wipe away the grease and you should be able to see the part number stamped directly on them.

If you are unable to find them, you need to use a digital caliper and measure your spindle to the thousandths of an inch where the bearings and grease seal ride. You can use the photo I've attached to see exactly where you need to measure.

For example, the Trailer Idler Hub Assembly for 2,000 lb Axles # AKIHUB-440-2-2K has a 4 on 4" bolt pattern, and uses inner and outer bearing L44649 (1.063" inner diameter) and a grease seal with a 1.500" inner diameter. If you had that you could swap it out with the Trailer Idler Hub Assembly for 2K Axles # AKIHUB-545-2-2K which has the same bearings and grease seal, but has a 5 on 4-1/2" bolt pattern.

If you let me know what you have I can take a look and see if there are any you can swap out, and I've also added links below to our selection of hubs and a help article on bearings I recommend checking out.

expert reply by: Kyle S

click to enlarge

Ridley M.

1/11/2025

What if I don’t know the weight limit on the axle the boat trailer was converted to a utility tilt trailer

Robin H.

1/12/2025

@RidleyM the bearing combination can also help you determine that. Typically hubs that fit the bearing combination match the capacity. Coming from a boat trailer it is probably 2k or 3,500 lbs. I would still check to see if there is an axle tag.