How to Measure an English Saddle Tree Width
A rider can determine the exact width of the saddle tree of a fully assembled English saddle only by relying on manufacturer documentation or markings on the saddle. Additionally, different English saddle manufacturers use different designations for saddle width measurements; the width of the same size saddle tree can have a different measurement designation between two different manufacturers. A rider can, however, determine the width of saddle tree needed on a particular horse and determine if a particular saddle comes close to fitting this requirement.
Tips & Warnings
Recognize that in measuring a fully assembled saddle, you can only determine the width by way of documentation included with the saddle or a marking on the saddle designating the width. Measure from the saddle nail on one side of the saddle to the saddle nail on the other side of the saddle, if for example you are dealing with a used saddle, to ensure the saddle tree has sufficient width to accommodate your horse across the back. The saddle nails are rivet-type metal pieces at the front of the saddle at the front of its skirt.
Bear in mind that no standard sizes exist for saddle trees and that each saddle producer sets the standards for the saddles produced by its manufacturing facility. Additionally, the introduction of adjustable width features in saddles, as of 2010, further obscures identification of the width of the saddle tree on fully assembled English saddles.
The width of the tree is only one of the size specifications necessary to determine if a saddle is a proper fit for rider and horse. Minimally, you need to have length-of-saddle sizing from front to back. This is the measurement normally used to identify a saddle's size, such as 17 inches.