Darnell Superior quality casters.

Twin (2) Rubber-fibre wheel. Features heavy duty, double ball-bearing swivel.
The upper row carries the load weight, and the lower row takes up all the side thrust.
Excellent for schools, churches or any facility that moves pianos frequently.
Darnell dual wheel piano casters are equipped with four sided double ball raceways.

• Wheel Diameter: 2"
• Wheel Face Width: 3/4" Each Wheel 
• Wheel Material: High Capacity Neoprene
• Load Capacity ea: 200 lbs. (800 lbs total for Uprights)
• Height Without stem: 3"
• Stem Dimension: 7/16" Dia x 1-3/8" Long
• Supplied with 4 removable, round CR-3 pressed steel sockets with lock notch.
• With a 2-1/8" Round Diameter Flange Base, With 4 Screw Holes ( screws not included )
• Screw Hole spacing on flange base  1-1/8" apart 
• OD: Of Stem 19/32"

All of our wheels are sold with their own sockets. You will be required to replace the entire wheel / socket assembly to ensure a proper fit.
You may be required to modify the existing hole in your piano to accommodate the new casters.
Unfortunately there is no reference manual to tell us what wheels would work in each of the over 12,000 pianos manufactured.