resizing textures with texresizer is easy and takes under 10 seconds /texture ....don't resize textures with max width that is in texresizer ...what I recommend you to do is:
1. open texture with texresizer .
2. right click on lod1 texture (2nd biggest texture out of those 4 you see)
and press save to tga and save it somewhere you want.
3. then right click on lod0 texture (that's the biggest texture you see )
and press load from tga and then just load that tga file you saved earlier .
4. after that just press downsample and press save .tex file and you are done.