Steps to Identify and Measure a Trailer Leaf Spring

Step 1: Determine Type of Trailer Spring 

Determine the type of trailer spring. What do the ends of your trailer spring look like? Below are images of the most common types of trailer springs.  You will need to know  if you have a double eye spring or a slipper spring with a flat, radius, open eye, or hook end.

Step 2: Measure Width of Spring 

Measure the width of the spring. The majority of trailer springs for boat, motorcycle, horse, camping, flatbed, and utility trailers range from 1-3/4 to 2 inches wide.  To determine the width, measure across the top of the top leaf.


Step 3: Measure Length of Spring 

Measure the length of the spring. If you are replacing a spring, getting the same length is important. To measure the free length, refer to letter “C” below. It is important that your trailer is unloaded when measuring the length. When determining length (C), measure from the center of one spring eye to the center of the other spring eye for double eye springs. Measurements will vary depending on the age and fatigue of your spring. We offer a large selection of trailer springs. Determining the length first, will narrow your selection down considerably and make finding the correct spring quicker.

Step 4: Determine Capacity 

Determine the capacity and how many leafs. Determine what type of capacity you require and how many steel leaves your existing springs have. If you are replacing all of your springs, the number of leafs will not be as important. You can switch from a 4 leaf to a 3 leaf with thicker steel if you prefer. The capacity ratings are per spring. Determine the rating of your trailer axle and then select the capacity of your springs. If you have a 6000 lb. rated trailer axle with two springs, use two 3000 lb. rated or higher trailer springs.


Step 5: Measure Free Open and Arc of the Spring 

Measure the free open (H) and the arc (A) and (B) of the trailer spring. These measurements are more for reference and will change with the age and fatigue of your spring. These measurements can show you the importance of replacing all of your springs rather than one at a time. If you have an older spring that has lost its arc over time and you add one new spring with a taller arc to the other side of your trailer, your trailer will lean to one side causing for an uneven load and unsafe conditions.

Trailer Spring Capacity 

The capacity rating is per spring. If you have a 6000 lb. rated trailer axle with two springs, use two 3000 lb. rated springs.


Change Springs in Pairs 

All springs are sold individually, but it is highly recommended to change them in pairs. Changing only one spring may cause your trailer to lean to one side due to the spring fatigue of the unchanged spring(s) and can cause excessive tire wear.




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