Garage door torsion springs need to “match” the weight of the door. They are used to make the door seem to be weightless, with the proper springs the door should be able to stay at half open with out the opener attached to it. If yours doesn’t, please contact me.
To insure the replacement springs are correct for your garage door, I will; weigh your door, measure the size of your door, measure the drum size, determine if the track arc is 12 or 15 inches and measure the current springs. With this information I can tell you the duty cycle of your current springs and recommend the best replacement springs, including the option of greatly increased duty cycle springs for only a few dollars more each. This will add years of trouble free operation for only a few dollars, and may keep you from having to replace the garage door opener if the current springs are under sized.
If the door has been painted one or more times it’s weight has increased. If decorative wood has been added, its weight has likely increased dramatically. The majority of garage doors from the factory come with 10,000 cycle springs, which equates to opening and closing the door twice a day for 7 years before failing/breaking.
For hours of reading on this subject, type “torsion springs for garage doors” into your favorite search engine.