There are plenty of discussions about the lack of a spare wheel and/or the puncture repair kit on Mk3’s
… but does anyone know if you can fit run-flat tyres? Do they require different alloy wheel rims?
I have had run flat tyres on BMW’s and they are brilliant.
Once we drove from London to Warwick and back with a flat tyre, on a second occasion we drove from Eastbourne to London in the snow in the middle of the night.
On both occasions we needed to make the journey on-time and could not stop and wait for a breakdown recovery truck.
OK, the disadvantage is the tyres cannot be repaired and they are not cheap to replace, but at least you can continue your journey.
I did some looking around and might as well answer my own question 
Fitting Run Flat Tyres to a vehicle (‘retro fitting’) that was previously fitted with ‘normal’ tyres requires:
1.Tyre Pressure Monitoring System
Run flats must only be installed on a car which has TPMS/tyre pressure monitoring system. TPMS alerts the driver to a puncture so they are aware that they have a limited time to replace their tyre, and so they drive within the limits of their deflated tyre.
2.Vehicle Suspension
You may need some changes made to your vehicle’s suspension. Because of their stiffer construction, run flat tyres contribute to a vehicle’s suspension when fitted as original equipment.
Run-flats on a sports car? Hmmm… I’ll look for you in the ditches 
Run flats are like kangaroo gonads, fine for the roo but you don’t want to put one on a plate.
Check out the Wheels in motion forum and see how much trouble and damage they cause.