I'm planning on doing a longer endurance race and handing over the cockpit to the AI during this time. Now to my question: How long is a stint at AI? Is it fuelbound if the tires are not a problem or how is the duration of an AI stint determined?
The AI will drive as long as you let them. They will pit and carry on if running out of fuel or tyres. To take back over, you will need to use the in car menu to select the swap drivers option again.