Some cars got updated their wheels in patch Z. They now have one repeating texture instead. You still can change that texture but it is not as much moddable now.
You still can modify steering wheel textures of UF, FZ or FX cars.
If I remember correctly, the "old" textures are Cromowheel2.dds and Cromowheel_grip.dds but I can't remember the name of the new texture, probably something with "leather" in it.