I have an 02 Liberty Limited 4x4 with 235/70 R 16 (29 x 9.25 x 16) tires. I recently got a set or wrangler tires that are 241/79 R 15 (30 x 9.49 x 15)

Here's how they compare...
Dimension................Tire A: 235/70 R 16 (29 x 9.25 x 16)......Tire B: 241/79 R 15 (30 x 9.49 x 15),,,,,,,,,,,Difference
Width........................9.25" (235.00mm).....................................9.49" (241.00mm)..........................................+.24"
Sidewall Height..........6.48 inches...............................................7.5 inches......................................................+1.02 inches
Overall Height...........28.95 inches..............................................29.99 inches..................................................+1.03 inches

So can I swap wihout and modificaions...

And just outta curiosity, I recently bought my KJ and noticed it's flares and and wells seem to sit and inch or so higher than most other ones. I heard some of the 02's came from the factory with a lift. Anyway I can tell (I'm new to looking under cars...)

I am going to tuch this one with as light a tuch as I can
first let me get this out of the way "241/79 R 15" "what??"

now I think that you ment to post up 245/70R16? if so then no problem swap no mods needed use OE wheels and go for it but remember that the OE wheels are 16" not 15"

as far as coming with a lift no not realy the '02 came with a higher or taller spring than the later models so yes you will be an inch taller when compared to stock '03 and newer but lifted you or them it will be the same ,look at OME springs to under stand
'02 get ~20mm and '03 and newer get ~40mm same spring PN different OE springs