IP Engineering help

[planty]

I've a Feanor engine and it needs some plasticard rework around the wheels.

Does anyone know the hole size required to snuggly fit the brass bearings for the axles? I need to remake the sides that hold the axles and to save trial and error wondered if anyone knew the size in mm that I need to drill?

Presume their budget chassis would be the same size so if you know the size of this too that would work.