Garage Door Torsion Spring Wire Size Chart
The chart you can see below refers to the thickness of the wire used to make the spring. As you shall see, there are over 30 different variations and each one is obviously specific. The best way you can use to measure the thickness is to measure 10 or 20 coils. Look for the side that isn’t covered with corrosion (as the springs moves, it will rub the inner parts and prevent corrosion from occurring). The chart you can see here is based on 10 and 20 coil measurements and it is expressed in inches and centimeters. The last section is the column with the actual wire size or better said thickness. In the table, there are 2 values marked in bold. They are equivalent to the naked eye when you measure them improperly. Make sure you measure 20 coil spring properly in order to avoid this error. In addition, the wires sizes: .237 and .200 are not used anymore. You will need a spring with similar or replacement wire size instead.
Here is a video on how to replace garage door torsion spring: