I get mine here:
https://www.sunray-inc.com/custom-pa...-drive-wheels/
I have rubber and polyurethane wheels and have used them for years. I detect no difference.
My main wheel is a smooth 8" polyurethane idler wheel with a 7" aluminum core. That equals a half inch of poly all around.
Sunray lets you order it the way you want it. Steel or aluminum core, you select durometer (hardness--I like 70A), drive or idler, hole size, bearings included or not, color of poly, tread pattern or smooth...
The wheel is custom and still costs less than the equivalent in rubber.
These is copied from a recent quote for a grinder project:
8.00" X 1.00" IDLER WHEEL / 7" ALUM CORE / 70A BLACK
POLYURETHANE TREAD / INCLUDES (2) 1621-2RS (.5" ID) PRECISION
BALL BEARINGS INSTALLED
$81.68 $81.68
1 2.00" X 1.00" DRIVE WHEEL / 1.5" ALUM CORE / 62A BLACK
POLYURETHANE (CROWNED TREAD) / .75" STRAIGHT BORE WITH
KEYWAY AND SETSCREW
$47.77 $47.77
1 2.00" X 1.00" IDLER WHEEL / 1.5" ALUM CORE / 70A BLACK
POLYURETHANE TREAD / INCLUDES (2) 1621-2RS (.5" ID) PRECISION
BALL BEARINGS INSTALLED
$35.67 $
USA Knifemaker's supply also deals in poly wheels.