No need for excuses Grubby
Ok John, Grubby and Inkworm ... thanks for those tips and advices with those tires.
Here is the new version of the theird moke-up, with new tires ...
used the micro tutorial from John and added a bit of dark and highlight to creat the 3d deformation of the lower part of the tire... and ok... cut a bit of the tire too.. can't resist, hope it appear to be realistic: