235/70/16 Front + 265/75/16 Rear?

[Seamonster]

My 2002 KJ Limited (3.7) is lifted 2". I needed two new tires, and ordered 235/70/16 KO2's to match the two good ones. The next day, the matching pair had not arrived at the seller's, so I let him talk me into a great deal on a pair of 265/75/16's, also KO2s, that someone had ordered but never picked up. (Sorry if this topic has been covered, but I searched for 15 minutes, and my available bandwidth has been low since I lost my house in the Palisades Fire in January – FEMA ***** up a lot of it.) Anyway, it all seemed great: with the fatties on the rear it looks kinda fun, and it rides fine (even the headlight angle is okay).

Our thought was that my next two tires could also be 265/75/16's, which would require cutting away some of the wheel well on the front (the rears are fine). Would I still have to do that with some intermediate size – 245/7X/16 , given my 2" lift?

Only later did I start to wonder (as I said, my available bandwidth has been low)...
Will the current mismatch affect use of 4WD?
How much (percentage) will it affect the speedometer's reported speed, and can I recalibrate that? (I know the speed sensor is on the rear.)
What would happen if I tried to put the 235/70/16 spare on the rear along with one 265/75/16 – complete havoc?
What about the re-gearing I read about on this site – is that a bull I'll have to grab by the horns?
What other quicksand have I gotten myself into in the name of a "great deal"?

Thanks, K

 

[Seamonster]

[Big Brother automatically inserted asterisks where I said that FEMA did that thing that vacuum cleaners do.]

 

[KJowner]

They aren't massively different in size & in 4x2 it shouldn't make any difference but I wouldn't use 4x4 until you have a matched set.
If the Jeep feels underpowered then you may need to regear, if you're happy then save a fortune and don't bother... or put standard tyres back on, a much cheaper option.
The spare will get you home but being undersized the diff will get a workout so go steady and swap back ASAP.
Size comparison:

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