A letter appeared in November BMW Car on the subject of RFT tyre repair.
It would seem that there is a level of ignorance that results in the "can't fix it" response.
The Guy in question went to a national tyre franchise who said no, and two BMW dealers, one who who said it could be repaired and one who said it couldn't. BMW Helpline were also vague on the point.
They then contacted the tyre manufacturer (Goodyear) who confirmed that the tyre could be fixed provided that the puncture was not near the sidewall, and the tyre had not been driven deflated over a long distance.
As an aside BMW claim that a 530d fitted with run-flats is 10seconds faster around the Nurburgring than one without (UK BMW magazine Autmumn/Winter 2005).
My 2p worth:
The only difference that I am aware of between run-flats and a standard tyre is the reinforced sidewall. The wheels themselves are also modified to ensure that a deflated tyre remains on the rim. Therefore they may be treated as any other tyre when considering a repair within the treaded area of the tyre.
However....... whereas you would change a deflated standard tyre immediately and take the tyre for repair this is impossible for the RFT with no spare. Therefore you should carefully consider any damage that may have occured to the tyre whilst running deflated. If you can keep pumping the tyre up and/or run at a slow speed there should be no problem. But if you have driven at high speed and loadings for some distance the heat generated through the extra flexing of the deflated sidewall and loads placed on it are bound to have a detrimental effect on the tyre.
I believe that this is why many tyre fitters will say that you have to replace the tyre. Even in the UK, let alone the litigous USA imagine what would happen should a run-flat fail having been repaired.
At the end of the day tyres are expensive, but you tust them with your life every time that you drive. Just use common sense.
Gone: Fiesta - Focus - E46 320dSE - E91 330dMSport - E82 135iMSport - R55 JCW Clubman
Now: M135i with lots of toys