Mobi said:
OK, I'll order those then :
You won't be disappointed! As Gareth said, they are a very quick and easy replacement - just gently spread the flexy plastic axle carriers and pop the plastic set out, then clip the new metal set straight in. As that bl**dy meerkat says, Simples!

While the Bachmann wheels look slightly less "refined" and shiny than the LGB sets, functionally they are great; unlike the LGB types which have metal rims on plastic wheel-centres and axles, the Bachmann type are solid metal throughout (except for the plastic insulating inserts of course!), and this gives them a little extra bit of weight - which can be very handy for keeping your rolling stock running true and reducing derailments.
If you have a lot of rolling stock to do, then it can be worth talking to a local model railway shop if you have one (even if they don't stock G scale, they will probably have an account with Bachmann for smaller-scale stuff and thus be able to special order items) - and just see if you could get anything off by ordering a full box of blister packs - which would (I think) probably have 10-12 packs in it, which would be enough for 20-24 pieces of 4-wheel stock or half that number of bogie wagons.....
Jon.