Axle Needed to Upgrade to 15 Inch Wheels on Homemade Utility Trailer

Updated 05/07/2020 | Published 05/06/2020

Question:

Hello, I recently acquired a boat trailer. The trailer is well built and has a strong frame, the frame is built with 5 c purlin. I plan on converting it to a utility trailer. Currently, the trailer is single axle and has 12 wheels and tires on it. I would like to put 15 tires on it. The fender can easily be raised. However, the lug pattern on the axle only has 4 bolts. The biggest wheel I can find is 13. Do you all sell a 15 wheel with 4 bolts. Or is it possible to just change the hub and drum assembly on the axle in order to get a different bolt pattern? Or would it be better to upgrade the axle to one that has a higher weight capacity? Any help is greatly appreciated. Thanks

asked by: Ray V

Expert Reply:

For a 15 inch wheel, you'll need a hub with a 5 on 4-1/2 inch bolt pattern. The hub you'd need wouldn't be compatible with your existing spindles, so your best bet would indeed be to go with a 3500 lb axle. To determine which axle you'll need, you'll need to know the hub face to hub face and center leaf spring seat to center leaf spring seat distance. I'll provide a diagram showing how to take each measurement.

The off the shelf axle beams we offer have hub face to hub face dimensions of 89 or 95 inches, with spring seat spacing of 74 or 80 inches. They can be had with either idler or brake hub drums that include the brake assembly.
I'll link you to our selection of 3500 lb axles.

You'll also want keep in mind that upgrading the axle beam and wheels/tires won't increase the load bearing capacity of your trailer. You'll be limited by the lowest rated component, be it the suspension, coupler or even the structure of the trailer of itself.

expert reply by: Mike L