In lugnet.trains, Reinhard "Ben" Beneke writes: Ok, I have now 12 wheel sets in front of me: ***...***+ 4x from a MISB Metroliner 4558 from ca 1991...1994 Never run a single meter so far.... Measured for all 4 wheel sets (no bigger difference (...) (22 years ago, 24-Oct-02, to lugnet.trains, lugnet.lego.direct)
A funny thing that I noticed wrt changes in train wheels happened right around 1996, specifically in set 2126 (the 4 train cars). It seems that the center hole is not "true" center or the wheels where not "true" round. I recall making several 2 axle (...) (22 years ago, 24-Oct-02, to lugnet.trains, lugnet.lego.direct)