How to Determine the Bolt Hole Pattern on a Trailer Wheel


I have a 1996 Load Rite tilting Flat bed trailer with side rails 6x12. The axle is locked into a position too far to the right so I want to install wheel adapter/wheel spacer to push the back right wheel out and away from the trailer a little. Does anyone know if it has a 4-1/2 pattern or if not, what size pattern it has? Thanks.

Expert Reply:

The Trailer Hub Assembly, # 8-259-5UC1, has a 5 on 4-1/2 bolt pattern. To determine the bolt pattern of your trailer wheels, there is a simple way to measure.

If there is an EVEN number of lugs, you will measure center to center on lugs directly across from each other. For example, if the wheel has 6 lugs and the center to center distance between 2 that are across from each other is 5-1/2 inches, then the bolt patter is 6 on 5-1/2.

If there is an ODD number of lugs, you will measure from the center of one lug to a point halfway between the two lugs directly opposite on the bolt circle. With an odd number of lugs, there is not a lug directly opposite of any hole, so finding the circle diameter can be difficult. For example, if there are 5 lugs and the distance from the center of one hole to the center point between the two holes across from it is 5 inches, then the bolt pattern is 5 on 5.

You can also measure the distance between the center of one bolt hole to the center of the bolt hole next to it. If the distance is 2-5/8 inches, the bolt pattern is 5 on 4-1/2. If it is 2-3/4 inches, the bolt pattern is 5 on 4-3/4. If it is 3 inches, the bolt pattern is 5 on 5. And if it is 3-1/4 inches, the bolt pattern is 5 on 5-1/2.

I have included a link to an FAQ article below that contains the measuring information along with some pictures that illustrate them.

Instead of spacers, the best solution is to find the cause of the wheel being too far in. Chances are since the one side is too far in, the other wheel is too far out. You will need to check the springs and spring seats for damage and to make sure they are attached correctly to the trailer. Check to see if the spring hangers have come loose or are damaged or if any of the shackle bolts or u-bolts need to be replaced. I have included 2 FAQ articles on trailer suspension below.

I spoke with our resident tire expert and he advised not to use spacers for several reasons. First, adding spacers will increase the chance of the tire coming loose. Also, since the load on the axle will no longer be evenly distributed, the axle will be derated and it will cause uneven wear along with reduced capacity. The best thing to do would be to adjust the axle position if possible.

expert reply by:
Michael H

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