The wheels are 3/4" diameter. The center to center distance between the wheels is 1 11/16". The center to center distance between the mounting holes is 1 5/8". The offset, from the outside face of the wheels to the outside edge of the plastic cover (i.e. on the opposite side of the adjusting screw), is 1 1/4".
Hopefully I have provided enough information. If you need anything further, please let me know.
![User submitted photo of their roller.](/images/pictures/2015/05/52345.jpg)