Let me quote the NATRC rule book:
Pads of any type are not permitted except rim pads. (a cut-out pad of leather
or synthetic material of uniform thickness is permitted when this material
does not exceed 3/16" in thickness and the material is cut flush with the
shoe inside and outside.)
The only problem you might have is that 3/16" is slightly less than 1/4".
-Jim
jferris@cwa.com
Morgan Hill, CA