How to Determine Correct Leaf Spring Size on 6 X 12 Utility Trailer

Question:

I measured my current worn out leaf springs and they measure right at 26 - 26 1/4inch long, theyre on a 6x12 utility trailer and do I need to stick with 26inch or go with 25 1/4? Thanks

asked by: Jay M

Expert Reply:

When replacing the leaf springs on your 6 x 12 utility trailer you will need to match all of the dimensions and the spring capacity as closely as possible to the original spring. Usually the measurement from eye to eye will lengthen and the height measurement will decrease with wear. See picture I have included that will show the measurements you will need to match to replace your leaf springs.

The number of leaves in a spring pack does not have to remain the same as long as the weight capacity is inline with the trailer and axle rating and the measurements match the existing spring hardware.

The weight capacity of the trailer axle will also help you decide on the correct leaf springs. The trailer will have a plate or sticker on it that will list the VIN number. The weight capacity of the axle should be listed on that same plate or sticker. Also, the axle could have a tag or plate on it that will list the weight capacity.

You can also tell the weight capacity of the axle by measuring the diameter of the axle. A 2,000-lb axle will have an axle diameter of 1-3/4 inch. A 3,500-lb. axle will have a axle diameter of 2-3/8 inches and a 6,000-lb. to 7,200-lb. axle will have an axle diameter of 3 inches.

I am including a link to a FAQ page on trailer suspensions and it will list the axle diameters for different axle weight capacities.

Also, I am including a link to a product page on leaf springs. It will have a chart that will show the sizes and capacities of the leaf springs.

A common size axle on a 6 X 12 utility trailer is a 3,500-lb axle. For leaf springs on a 3,500-lb axle with an eye-to-eye dimension of 25-1/8 inches, I recommend the 4-Leaf Spring, part # e54SR. This spring has 4 leaves and is a double eye spring. You will want to make sure the measurements on this spring match the measurements on your existing leaf springs.

It is recommended to replace leaf springs in pairs to ensure a balanced load on the trailer when towing.