baking problems in istamat

I have never used that software sorry, perhaps Chunck has or any of the other guys. 

You shouldn't need to change much on the Instamat settings. Although you could try adjusting the ray length a little, but I think the issue is likely to be with the exported models and in Blender.

Can you show a screen shot of your Blender with both high and low models and the bake settings?
Better still, share the .blend file via google drive, dropbox or similar, and paste the link here?

I don't think this is the issue,
however your exported models have suffix _low1 and _high8, either remove the number or add it to the target and source mesh suffix in the advanced settings.
It is important that the suffix is correct.

Hi John,

Looks like Adrian is correct:

your Low Poly tire is way smaller than the High Poly:

Yes! That will be the problem.
It is mentioned in the course for the low poly profile should match or slightly larger than the high poly.