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]

[The forum software 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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[Seamonster]

Hey KJowner, thanks for all that detail – just seeing it now. A few days after my post above, I thought the better of it all, and went back and exchanged the rear fatties to match the front 35/70/16's. It did look kinda cool for those few days, but I didn't think to take any pics of it.

 

[DefCon2]

Smart move. That was much more than a little size difference. It was literally just a hair less than 10%. That would have been devastating to your driveline in 4wd.

 

[WheelNut]

245/75R16 and 265/70R16 are the same outer diameter: 2mm difference, which is well within the tolerance for tire wear front to rear. 245/75R16 is pretty darn large for the Liberty as is, but it is workable and will rub a bit offroad (better if you use stock rims). I have no idea how well 265/70R16 would fit in the rear. I would imagine that the tire will rub the fender flare pretty good when articulating the rear axle. You could use a 245/75R16 as the spare as that will fit a bit better. It would definitely look cool!

 

[DefCon2]

245/75R16 and 265/70R16 are the same outer diameter: 2mm difference, which is well within the tolerance for tire wear front to rear. 245/75R16 is pretty darn large for the Liberty as is, but it is workable and will rub a bit offroad (better if you use stock rims). I have no idea how well 265/70R16 would fit in the rear. I would imagine that the tire will rub the fender flare pretty good when articulating the rear axle. You could use a 245/75R16 as the spare as that will fit a bit better. It would definitely look cool!

That is interesting to ponder. Since clearance is more of an issue on the steering axle, a .8 narrower tire could make a difference. Thinner tires in the front and wider in the rear would hardly be noticeable visually. I wonder how much the contact patch would differ. And of course it would mean that tire rotations could only be performed left to right and not front to back.

 

[sota]

... it's a jeep, not a mustang. Please don't do this.

 

[DefCon2]

... it's a jeep, not a mustang. Please don't do this.

Why do you say this? The talk is about front wheels that would look exactly like the rear wheels, with a minor difference in width. I hardly think that a .8" difference in width would look anything like a Mustang. It wouldn't be noticeable to the naked eye, only to the control arms and and shock mounts and other hard parts that reside within the wheel arc.

 

[sota]

and now you can't do a proper tire rotation. which means the rears wear more than the fronts. which screws with the transfer case and driveline when in PT 4WD, or runs the diff more in FT 4WD.
if you're not doing it "for looks", then why do it at all?

 

[DefCon2]

Go back and read my original comment. It accounts for these questions.

 

[seafish]

The talk is about front wheels that would look exactly like the rear wheels, with a minor difference in width.

Its not the width but rather the height of the tires that can be a problem.
Running different sized tires front and back while in 4wd will tend to stress the transfer case and drive line.

 

[DefCon2]

Its not the width but rather the height of the tires that can be a problem.
Running different sized tires front and back while in 4wd will tend to stress the transfer case and drive line.

Of course it does. The difference in circumference is the actual measurement that matters. The OP addressed this and said that the difference is well within the acceptable tolerances. And if anyone believes that all four of their tires have the exact same circumference, they are dreaming. Wear, damage, and even tire pressure can easily alter the circumference of a tire well more than the listed differences of these two sizes.

 

[seafish]

Will the current mismatch affect use of 4WD?

A few days after my post above, I thought the better of it all, and went back and exchanged the rear fatties to match the front 35/70/16's.

Smart move. That was much more than a little size difference. It was literally just a hair less than 10%. That would have been devastating to your driveline in 4wd.

@DefCon2 WTF Im not at all sure whats got your dander up … As these quotes show, this thread has been a little more then confusing.
I was just clarifying the point about mismatched tire diameters on a 4WD being more important then mismatched widths. Even you indicated …

That was much more than a little size difference. It was literally just a hair less than 10%. That would have been devastating to your driveline in 4wd.

 

[DefCon2]

I have no idea why you think my dander is up. I am only responding to people who replied to me or commented on my post. But I do have to correct you when you misquote me. You referred to a comment that I made when the topic was a 29" tire versus a 31" tire. Then the topic shifted to two sizes that have a 2mm difference in diameter. The first example is a stark difference that could cause the problems with the driveline that you mention. The second is not. And I say that with my dander slicked down with Brylcreem.

 

[seafish]

Then the topic shifted to two sizes that have a 2mm difference in diameter.

K that's what I missed.