[Graham]

It might have been interesting if at the time you asked the participants whos tyres became unstuck exactly what adhesive THEY used, maybe eliminating some of the glues, or finding a common denominator.

I did at the time, and there was different types of adhesive failure for some adhesives. But it would not be right to necessarily blame one adhesive or another if the preparation was not the same.
And that would have been a major reason to do the the test.