2 Answers

 Cook the red potatoes over medium high heat until they are easily pierced by a fork but still are a bit firm. Usually it will take about 20 minutes for the potatoes to cook. Make sure you don't overcook the potatoes.    The size & age of the potatoes will affect how long it takes. You want the fork to go in easily, as if it were your teeth while eating the potato, but you don't want the potato to crumble & fall apart when you stick it.

(but the size & age of the potatoes will affect how long it takes). You want the fork to go in easily, as if it were your teeth while eating the potato, but you don't want the potato to crumble & fall apart when you stick it.

And I do not think that it matters that they are "red", and it depends upon how much water, size of pan, the altitude that you live at, and amount of potatoes in pan.  But it is really much more simple than it sounds.  Follow the link above for greater information.