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different tire size up front than the rear

4K views 9 replies 6 participants last post by  Water Dog 
#1 ·
Ok guys, I'm not totally new to the forum life, but I am new to this one. I'm currently looking at trading my 2nd vehicle for a 2004 wrangler sport. I currently drive a lifted F250 and love it, but it is to big to drive through the trails at our second property. I have always loved the wrangler and always dreamed of owning one. The wrangler I am currently looking into seems to be built for rock crawling and located at a dealer 4 hours away. It has the poison spider front and rear bumpers, no carpet on the inside, and skid plates underneath. The only concern I have is that the front tires are 35" and the rears are 33".

My question is, "will this harm anything if you engage the 4x4 or will this be fine if the previous owner played with the gearing"?
 
#2 ·
The front and rear tires need to be the same diameter or using it in 4x4 could prove disastrous to the transfer case. Changing tire diameter by 2" is the same as having different gearing front and back, and unless someone went to the trouble of doing the math and came up with different available gearing that just happened to work with those two different tire sizes this is a wreck waiting to happen. Even if that were the case, why buy something that had two diffs with different ratios...I would just look elsewhere.

At bare minimum put it on a rack and determine what the diffs are geared to, and get the seller to put the same size tires on it. Also make sure if it has 35's on it, that the rear diff is either a D44 or Ford 8.8. A D35 rear axle used on the majority of the TJ's is not up to running 35's.
 
#4 ·
Hmm that seems odd, I've never seen anything like that personally. The front and rear wheels need to move the same linear (or tangential) distance at the same rate. This means your front wheels will be turning (angularly about the axle) at a slower rate than your rear wheels.

In order for that to work, for each revolution the front wheel makes, the rear wheel must make roughly 1.061 revolutions (given each tire is the exact size as it's stated to be, which they never quite are).

I'm not entirely sure what the difference in gear ratio would need to be to satisfy that.

But as long as that checks out, as far as my knowledge goes, it should be fine. However I'm sure you'd want to having matching tire sizes before long. And between re-gearing and new rear tires thats another 1K or so.
 
#5 ·
That's what I was thinking Water Dog. I always grew up with the assumption that all 4 tires had to be the same all the way around on a 4x4. I'm assuming that the previous owner did this just for look since it's located pretty close to Miami. We always added a body lift to the front if we wanted the front higher than the rear (bull dogged where I come from). I may try to bring the dealer down in price for this and just buy two 33" tires for the front before if I decide to follow through any further.
 
#8 ·
I bit the bullet and pulled up the carfax on it just to give into curiosity. I just called the dealer back and told them I will not be perusing this jeep anymore. Those 2 different size tires kept getting to me on a odd way. Come to find out, the jeep was totaled back in 08, has had 4 owners, and the dmv has reported the odometer to be wrong, along with going from a salvage title to a reconstructed title. Time to move on and start looking else where...lol
 
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