Mismatched Tires - No 4WD???

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Black & Tan

NAXJA Forum User

Location

Connecticut

• Dec 14, 2004

• #1

I recently upgraded all 4 tires to 235/75/15 and when I picked my Jeep up, the mechanic told me that if I ever had a flat and used the spare (which is still 225/75/15), I would not be able to use 4WD. I don't remember the reasoning he used, but basically said it was a mechanical limitatoin. Is this true?

 

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Digger87xj

NAXJA Forum User

Location

Buffalo Creek/Lakewood CO

• Dec 14, 2004

• #2

uhhh... sorta

if you have an open diff...no LSD or locker... you can use 4x4 but the spider gears are going to be working overtime.

if you have an LSD or locker...no, you can't use 4x4, nor should you be using a smaller tire.

 

B

Black & Tan

NAXJA Forum User

Location

Connecticut

• Dec 14, 2004

• #3

Thanks...I should have an open differential. It's not a limited slip nor an upgrade. Just stock. And I'm not planning on driving in 4WD with the spare in the immediate future, but I wanted to know what my options are.

From what you're saying, it sounds like I could use 4WD in an emergency with no damage, but it would be preferable to avoid using 4WD until all the tires are matching. I plan on purchasing another 235/75/15 after the winter, once the prices on the Bridgestone Revo's have dropped.

 

seanR

Want to puff on my pipe?

NAXJA Member

Location

29°58'28.9"N 99°15'15.5"W

• Dec 14, 2004

• #4

If all you want is a spare, go to a junk yard, $35.00 at most, used tires are hard to get rid of and they will gladly sell you one.

 

xj92

NAXJA Forum User

Location

Junction City, KS

• Dec 14, 2004

• #5

A 235/75R15 is only .6" taller than a 225/75R15. Digger was right, but it won't hurt you at all to use it in an emergency, even for quite a while. It's not the ideal setup, but it won't hurt anything.

 

techno1154

NAXJA Member

NAXJA Member

Location

In the islands

• Dec 15, 2004

• #6

Most XJ's came out with a donut spear. Think about it. My $0.02

 

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Drewlee77

NAXJA Forum User

Location

Abilene, TX

• Dec 15, 2004

• #7

A "donut spear" huh? No wonder so many Sheriff's use Cherokees! :laugh3:

 

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dmillion

NAXJA Forum User

Location

Colorado

• Dec 15, 2004

• #8

techno1154 said:

Most XJ's came out with a donut spear.

Click to expand...

Yeah, but the owner's manual for my '01 specifically says not to use 4WD when you have the doughnut spare (although, personally, I like the idea of a "donut spear!") mounted on the Jeep.

The bottom line is that the difference in the size of the tires is not enough to create a problem. If you have a 231 t-case you shouldn't be in 4WD unless there's enough slippage front-to-rear to make up for it anyway. And if you have a 242 t-case then run it in FT-4WD and it'll be fine.

 

red91

NAXJA Forum User

Location

exact location unknown

• Dec 15, 2004

• #9

I hear you can get donut spears from Krispy Kreme. Get a real spare, driving on the donut with tires larger than the spare will make you list to one side if it is considerably smaller.

 

techno1154

NAXJA Member

NAXJA Member

Location

In the islands

• Dec 16, 2004

• #10

red91inWA said:

I hear you can get donut spears from Krispy Kreme. Get a real spare, driving on the donut with tires larger than the spare will make you list to one side if it is considerably smaller.

Click to expand...

Nothing beats a full size spear. Both my XJ's came with donuts. My frist trip out was to a bone yard to get a full size spear. It is called peace of mind in the middle of the night on the highway at 75+ MPH.