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Discussion Starter · #1 ·
New to this forum and just bought a 93 Wrangler with a 4.0L and manual trans. Its stock so I assume it has 3.07 gear ratio. Question: what are the largest tires I can put on without having to change the gear ration?
 

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Might want to ask the TJ guys. Or maybe the CJ guys. But the YJ'rs def would know. Maybe a JK guy knows too.
 

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You can put 33x12.50x15 w/o having to re-gear, but you will lose torque. Now that is with a 4in suspension lift, if the jeep is stock height I know 30x9.50x15 will fit.
 

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Advice someone gave me when I started talking about larger tires was "regear, regear, regear."

I have a 94 2.5L that had 30.5x9.5x15 tires on it when I bought it. The jeep worked ok with the 4.10 gear ratio. Just had to remember to add about 5 mph to the speedometer to avoid getting tickets.

It generally had plenty of power. However, I live in the Dallas area and we really don't have any "big" hills to contend with. So I do not know if I was having a power issue but just didn't ever get to the point where it was noticed. Acceleration was not stellar... 0-60 in about 90 seconds... definitly increases your prayer time each day if you drive it to / from work and have to merge onto an interstate. You will hear that these jeeps have the aerodynamic properties of a brick... more like an 8" concrete block. They are not kidding.

Like many people, I decided the jeep would look better with bigger tires, so the first step was to add a 4" lift. That will allow me to put up to 33" tires on it. I recently replaced my tires with 31x10.5x15 tires. Evidently that was just enough to tip over the power edge. I would have to drop out of 5th gear for anything but a small hill... occasionally had to drop down to 3rd if running against a strong headwind. Mileage also dropped... from about 16 mpg to about 12 mpg.

I had the differrentials regeared to 4.56 ratio. The jeep actually feels "sporty" now on accelleration. Occasionally on medium hills where it is a long grade, I may have to drop back to 4th gear to maintain highway speeds. With a tuneup, new fuel filter, and new O2 sensor, I am getting 20+ mpg.

I could have probably "tolerated" the power loss and the mileage cut. But I was planning on driving my Jeep on my vacation this year. It probably would have made it much less enjoyable and certainly more expensive on gas. The new differentials did pretty good on my trip through New Mexico, Arizona, Utah and Colorado last month. So for me, regearing was worth the investment. Would I recommend it to a friend? You betcha.
 

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you won't notice the torque loss until you hit highway speeds and go up a medium or larger hill. also headwinds to be a real pain. Personally I just get a bit more speed going down hill to make it up the hill, or I just grab 4th. My Mpgs are fine I get an average of 17, you have to know that without changing to speedometer gear the speedo will be off. So the mileage must be compensated for by multiplying the jeep mileage by the compensating number, mine happens to be 1.15 but you have to find that number on your own jeep. Grab a gps and drive exactly 10mi according to the jeeps odometer then see how far the gps says you have gone then divide the gps number by 10 and you have the compensated number.
 

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Discussion Starter · #8 ·
Looks like I will have to include re-gearing in my budget... I live in the mountains, so it's a drive up hill to get home. OK.... now another question. There is talk out there of swaping axels out with a Ford rear and a front from a Jeep with a 4 cly.... is this worth it?
 
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