Modeling the treads has the advantage of being usable at all viewing distances and isn't much trouble.

A quick rundown of the process in Blender.

1. Open Blender split the main screen into two windows and change one to UV mode.

2. Import the mesh from the geometries folder to avoid any posing that DAZ or Poser might do on loading a file.

3. Press NUMPAD 1 then NUMPAD Period to frame and center the obj

4. Select the tires, press CTRL+I to invert the selection then press H to hide the selected parts, you should have nothing but the tires visible on screen now.

5. Select the tires, if you are lucky they have been mapped and will show in the UV Layout window.

6. If the tires need to be UV mapped  use ALT+LMB to edge select the ring at the junction of the tread and sidewall then press CTRL+E+1 to mark the seam. Do the same for the other side of the tire. Mark a seam across the treads at one point and mark the seam.

7. Unwrap the tire in edit mode by pressing U key with the cursor in the 3D view window and choosing your preferred unwrap option. You should have two circles and a long rectangle in the UV Layout now. Arrange these for easy texturing in your paint program.

8. Now to the modeling, if the mesh has enough polys in the tread area simply move them as you need to make the treads. If the tires are too low poly in the tread area use the K key to open the loopcut dialog and add as many loops as necessary for your needs. The new loops will automatically update in the UV Layout window.

9. Make your modifications, select all the tires press CTRL+N and recalculate the normals to ensure they all point the same way.

10. ALT +H to return everything to visibility, save the UV Layout, export the model.

TEXTURING

1. Open the UV Layout you saved in an image editor.

2. Add your photo images of the sidewalls and tread over the UV Layout and adjust to fit.

3. Save the manipulated and combined image as your diffuse map.

4. You can use this map to create the bump or displacement map also if you wanted to have raised letters on the sidewall for instance.

5.In DAZ Studio load your model, select the tires under the Surfaces tab and load the tire image you created in the diffuse channel.

6. Do a quick test render, if seams show on the tires at the sidewall - tread junction re-open the map and adjust the image so the photo extends slightly past the edges of the wire of the UV Layout.

This should have covered everything, if you run into a problem or need something clarified give me a shout.