This being the year of the up-sell, it appears to me Jeep downsized from the 32" 255/75R17 tires on the JK to 31.5" 245/75R17 tires on the JL to make the Sport specs (ground clearance and angles) more unattractive than the high-profit Safari (32") and Rubicon (33"). There appears to me to be few tires in the new size with less than an E Load Range, appropriate for our diesel F250, but not a lightweight Jeep.I can't find an option for better tires on the Sport B.
I could be wrong, but I'd bet the 255 size works fine on the JL Sports. The 265/70R17 tire size used on the 10th Anniversary Rubicon are wider, typically with a wider tread and with a 31.5" diameter probably also clear. They may require some modding to fit on the spare tire carrier.
The Goodyear Duratracs (we have on our F250) are popular with the expedition Jeep crowd because they're a little better than most A/Ts in mud while still being a great tire for on-road use, especially in snow. All that being said, the tires that are the subject of this thread look decent and I might not be tempted to replace them with Duratracs. The downsize is mostly academic and should make little difference in the real world.