Never used the stuff before and the boots for the E91 need changing, so if this is a better route to go down then I think I might do it instead of keeping with run flats.
Once you have applied tyre weld, is that it for the tyre? If it turns out to be nail and you use the weld, I guess you then have to get a new tyre and can't have the nail removed and plugged?
I had this on one of my run flats. Turned out I had a screw in the tyre which the tyre shop took out and plugged.