Updating wheels is harder as you have to do animation with FBX. So do the edits for the wheels same as the frame. I make a new material with a new name (wheels.m.pbrmetal) and only pick the color texture for now, normal and PBR will be from Substance Painter (SP). Note that the wheels do not need much of a normal or AO but you have to have them.

Clear all animation links.

Re do UVmap.

Make an ID map.

Export only one set of wheels, that is 2 wheels and axle.

Open in SP.

This is after backing.

 

In SP add Steel Rough with a color selection.

Note that line in the red circle is do to UV projection change to tri-planer.

Add in painted steel.

 

Note the white rim do to ID map being off one pixel, fixed in Photoshop.

In game color check.

 

After making the green channel litter for the panted steel.

Next up animation.