
You can optimize your gaming experience by enabling the HD textures with the help of texmod. 

1. First make sure you have it installed on your computer and launch the Texmod.exe
2. Select the "Package Mode" tab
3. Click on the big folder at the upper left corner of the window labeled by "Target Application'
4. Browse through the files and select the speed.exe from your game folder
5. Now extract the required HD package (tpf file) of your choice to anyplace you want
6. Click on the tiny folder at the screen center and select the extracted HD package
7. Click Run and wait some secs

Done!

Info:

DEFAULT .TPF:
Most recommended for those who likes Hi-Res Textures however, doesn't likes wait for a long period

The textures has the same resolution than the ones which is in the original .bin file however, it is not compressed as dxt3/dxt1, so it won't look too pixelated...
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HD PACKAGE .TPF:
Most recommended for those who are in the middle and does like of an optimized texturing work.

The textures are 2 times bigger than the ones which is in the .bin file (Except Liveries), the estimated loading time is about 1~2 minutes.

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SUPER HD PACKAGE .TPF
Highly recommended for those who are picky and has some patience for waitings.

The textures hare 4 times bigger than the ones which is in the orginal .bin file (Except Liveries, they are 2 times bigger) however, is recommended a decent PC in order to avoid the FPS drops.