I can confirm 112s have cast-iron wheels.Martin
I went dashing back to post #172, and learned a great deal. Your blue 112 looks absolutely wonderful, like new. Pre 1923 GNR, therefore the one I am looking at is at least 104 years old - but the catalogue does say cast-iron wheels, so no Mazak worries at least.
Many thanks for your very helpful reply.
John
There is also one in my post #765.
Martin
PS There is no special prize for posting the 1000th reply in this thread!