silversand,
Sorry, we were out in my toy barn and just came back in and seen your question.
Yes, the 265's with NO alterations needed at all and they clear by more than enough needed. 285/75/16 "E" tire on the front is a different story. You have to lower (crank down) the front torsion bar for clearance which gives a stiffer ride which is not wanted by us and also trim some of the plastic inners to clear when turning sharp like in a parking lot. That's why I won't use them.
New 245's VS new 265's:
The 265's alone being taller (larger dia by 1.18" 30mm) alters the speedometer and odometer roughly 3.9% VS 245's NEW to NEW. 774 rev/mi on new 265's VS 804 on new 245's. Reads about 2.5 mph slower indicated at 60 mph than it did and it also alters the overdrive engage actual speed. Overdrive engages at about 56 with 265's and with the 245's it engages at 53. No biggie but you have to drive the speed limit now not 4 or 5 over to be legal especially with new 265's. Also have to add about 2.5% to the odometer indicated traveled distance. Of course that's assuming you OEM tires gave you the true speed to begin with, ours did.
New 265's VS worn 245's:
The info I wrote is also because there's even more difference as you are going from worn down tread 245's which also means a smaller diameter tire yet (more rotations per mile traveled) to a new full tread larger dia tire. The total difference you will see going from worn 245's to new 265's is about 3.9% for size + 2.5% for worn = 6.4% (about 2" larger dia from worn tire) and decreases as the new tires eventually wear down. Now it's between 4 and 5 mph difference etc and can get you a speeding ticket.
Again: Assuming one has worn a 245 tire down in tread depth only 3/8" (.375" about 10mm) 80% of the .468 new tread depth, that's 3/4" (19mm) in tire height alone for wear which adds to the difference after the change by another 2.5% or alters the indicated speed by 6.4% total. Between 4 and 5 mph at 60 mph. Just be aware of it. Also, 265's have a wider tread which means less lbs per square inch of tread contact to the road so they don't squish as much as 245's do. All adds up! Less friction and tire squish/sidewall flex means less heat build up and less wear and tire carcass weakening.
There's a lot to it with a tire size only change.