If you are using GP3Edit, don't export the internal Hardware Wheel Graphics tires (in the wheels tab)) directly.
Note that you will generate a .bmp for whxx0 and another .bmp for whxx1 images. Observe that whxx0 is the "stopped" tire image, while whxx1 is the "running" tire image.
You have to save these tires graphics in .bmp files.
Then open these files and see a purple thin strip in the middle of the image, plus a large puble strip in the right side.
Edit the image by replacing the purples stripes with some tire texture (this can be done easily with Gimp or similar)
Save this file over whblur0.bmp, whblur1.bmp, whblidg0.bmp or whbridg1.bmp according you want to replace original goodyear or bridgestone tires respectively.
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