Sorry, but I don't see where GSERS or any ERS has any obligation to provide towing service so you can have new tires installed. Their obligation is to replace a flat tire with an inflated spare. If you don't have a spare because the manufacturer (BMW) has chosen not to include one, then it is up to you or BMW to provide tow service to the dealership. It would be different if you suffered a mechanical breakdown. It that case they would tow you to the closest authorized service center. This is spelled out very clearly in the membership materials provided to you at the time of enrollment.
