Just to be clear, Slater's Finescale wheels are just that. They are not intended to run on S7 trackwork irrespective of the length of the axles. Most Slater's loco wheels purchased from Slater's will need refining to meet S7 standards. However, as Graham stated above, specially manufactured S7 wheels for popular prototypes are available to members through the S7 Stores. Here is a link to the current list of available S7 wheels.
S7 Group Slater's Wheels
Dave
S7 Group Webmaster