"...std 888 wheel.. takes 2 hands to lift (and its still a struggle!)......." 
  I'm surprised you can pull the clutch in then!
 Too much looking at glossy pictures, maybe?
 
  I almost beat you to Celeste's wheels, but the aggro of getting two carriers made up so I can change gearing at the track quickly was too much for me - I'll just have to carry on with the cast lead ones......... 
 Weight of new setup depends how much rubber is left ! 
 Cheers, Paul