With the fan I'm running I used the ambient probe and cooked the ribs on timers.
It was easy we picked up preseasoned baby backs from Walmart and the method is called 2/2/1, the middle tinfoil time dictates how tender you want them, if you want less tender more competition style you could do 2/1.5/1, for us the 2/2.5/.5 was perfect.
Towards the end the charcoal was out of gas it was running at 240 for the last half hour.