The Axial wheels look like they have offset, but when I emailed Axial yesterday to check, they replied saying that those wheels have zero offset.
I also emailed Wheelspin models, who replied: " Unfortuantely we don't know the offset on these, and it's pretty tricky to measure accurately.
We have, however, fitted plenty of these to Traxxas REVO's and they fit absolutely fine, so should work well on your Summit."
So all in all the people who make and sell the product do not have a clue apparently.