The best way to measure the width of your rollers is by taking one out and measuring it. If you cannot remove the roller, another option would be to open the door halfway so they are at eye level to make it easier for measurement. You will need a ruler or tape measure to get an accurate reading on what size replacement rollers you’ll need to buy.
The average roller size is one inch, two inches, or three inches; however, they normally come ¼” shorter: ¾”, 1 ¾”, and 2 ¾”. The stem’s typical length can be measured by comparing it to the new stem. If they don’t correspond, older doors may necessitate custom-sized rollers. In this event please reach out to DoorFlex Garage Door Repair.