The next thing you should do is get it fixed...
The RS4 comes with a "Tire Mobility System" (can of sealant, instructions, and a compressor) located under the floor in the trunk.
In the owner's manual:
it's good for foreign objects up to .16"(4mm) and the object can stay in the tire.
do not use kit if there is any damage to sidewall from driving without air.
it's only a temporary fix and to replace the tire ASAP
avoid speeds over 50mph, heavy breaking,full throttle acceleration,fast cornering, and foreign objects that may damage other tires.
I'd suggest just calling 'free' Audi 24hr Roadside Assistance 800-411-9988 and having them tow it to a dealer. Pretty sure all they need is the VIN from the car.