Paul Willis
I also agree with the gauging of plastic centred wheels in the theory of some ‘bounce’ if a gauge is forced between them too firmly.
Which is why you should never use a gauge when it is a force-fit. Even an interference fit is by definition distorting the parts involved.
What is needed is a close sliding fit. If you have the ability to sense that, then your track and wheels should be true to dimension.
Best,
Paul