I am serving ribs at a party, but I can't be at home that afternoon. If I cook them the day before and then finish them off right before party, will them still be tender?
The easy (but potentially expensive) answer is sous vide. If you can carefully control the temperature, you can cook your ribs for 24-48 hours before finishing and serving. See this recipe for an example.
If sous vide isn't an option, you can still chill and reheat the ribs. There are several brands of pre-cooked refrigerated ribs in grocery stores that exemplify this. I believe the texture would be more firm, but it could still be very delicious. For the sake of safety, please chill them as quickly as possible. If you stack them into a large pile, it will take a long time to chill, giving bacteria a chance to grow.