Have not tried to put a stock TH wheel and tire in the spare tire well. Waiting for the answer.
Yes, they do fit. I have a 5th stock Trailhawk rim, with 245/75/17 tire on it, and it fits in the wheel well fine.
2015 Cherokee Trailhawk:
Granite Crystal, 3.2L V6, 8.4 Nav, black leather, sunroof, tow, tech, comfort/conv, no hood decal, 9 speakers, CD player, Maximum Care lifetime warranty, Mopar first aid kit, rear rubber cargo mat, Thule Aeroblade cross bars (black), Thule Rapid Aero feet, Kuat Vagabond X cargo basket, RRO rock rails with smooth covers, Mopar door sills, Raingler ceiling net, Raingler seat headrest handles, MFC aluminum lift kit, RRO winch bar and Warn M8000S winch, BFG T/A KO2s