cars are opaque in photoshop and texresizer

I'm trying to change the numbers on some of the cars. I open up the Tex files for a car in texresizer and change the file to a tga. I then open up the file in photoshop and it appears opaque. The numbers I insert however, do not. I then change the tga back to a Tex file using slimtex and open up the Tex file in texresizer and the image is still opaque yet the numbers I inserted are still bold. I am sure I'm doing something wrong or missing a step somewhere, so if someone could give me a few pointers in the right direction it would be greatly appreciated. I haven't run the car in the game yet as I assume that if it is being displayed as opaque in texrizer and photoshop it would most likely be the same in the game, if it loaded at all.

Thanks for any assistance.

Photoshop displays the RGB layer by default, so it doesn't look transparent as this layer only store color data.
Transparency is handled by the alpha layer that you can see in the Layer panel. This one stores transparency via shades of grey (white is opaque, black fully transparent)