Hiya,
I've got 5 x INSA TURBO Special Trac 285/75 x 16 (33") for sale, used but good condition with almost full tread left. Never used on road. Black steel modular wheels. These will fit straight on a defender but Discovery/ RRC will need body/suspension lift and probably wheel arch modification. Drymen/Stirling area, may be able to deliver for costs.
Also got 4 bare discovery 5 spoke alloys for sale, reasonable condition but could do with w repaint - £50