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Unread 01-12-2013, 07:09 AM   #31
hotrod351
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ive had both sizes on my jeep. for me at least there was a huge difference between the 31" and 33" for off road. the 33" were much much better.

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Unread 01-12-2013, 08:34 AM   #32
mvigo
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Colt44,

I thought I would post this link for the proper gear ratios given any tire size: http://www.offroaders.com/tech/gear-ratio-chart.htm

You may or may not have seen this chart but by looking at it you will see that if you don't re-gear you will suffer greatly in performance by going with a bigger tire size. I myself have 32" tires and love them. I agree with Keith that they look "just right" but, like someone mentioned earlier, they are getting harder to find. I run 3.73's with a T-5 and if I had to do it all over again I would regear to 4.10's. I do OK on the highway but really can't muster much above 65mph. At 55mph, the Jeep is great, faster then that though and performance drops off significantly. I mention this because you said you were using it mainly on paved roads, highway and some mild trails. Lastly, keep in mind, your mileage will decrease pretty good. I currently get between 12-14 mpg.

If you do decide to go with more of an off road type tire, I highly recommend you look at the Cooper STT. Cooper tires are made here in the USA and I have had great success with mine. I have had them now for 30k miles and they are 3 1/2 years old. It looks like I still have half the tread left and I rotate every 5000 miles. My CJ is my DD and my trail rig. For the most part it sees pavement but I also wheel it every chance I get so I have been pleased with the results so far.



Coopers A/T tire does not come in a 32" size unfortunately. I have also run Bridgestone Revo's previous and loved them but I switched to Coopers A/T on the family Honda Pilot and loves those.

Good luck on your decision, I know it will be well thought out.
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Unread 01-12-2013, 11:37 AM   #33
Colt44
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Mvigo -

Your chart doesn't go low enough to show a proper tire size for a 2.73 rear end.

It looks like it might hit the yellow region at about 26 inches, and the green at maybe 24, which is smaller than stock!
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Unread 01-12-2013, 11:43 AM   #34
Colt44
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Obviously my 2.73 differential is a factor. I'm not sure how much it matters, but I should have mentioned I have an automatic transmission.
(I know people around here disrespect the auto, but I'm in the Mississippi Delta and autos are great in the mud.)

This gearing may not be optimal for rock crawling, but we have very few rocks here; they're at the bottom of about 1000 feet of mud.
I can get the CJ out on the highway and cruise at 75 with no problem, so I think it's a good compromise given my usage - it spends a lot more time on the slab than in the mud.
But I can get on I-55 and make good time getting to the hunting camp, and still get around once I'm there, so I think it's okay.

Looks like I'll be deciding between the Firestone 31s and the KO 32s.
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Unread 01-12-2013, 12:17 PM   #35
jacques25150
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re

mine is with 235/75 equiped (approx 31) and no lift: it is good for the look but it is just when my car is charged and I have ordered a little lift at Jim (crabtree)
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Unread 01-12-2013, 01:17 PM   #36
BubbaK
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Quote:
Originally Posted by Colt44
Obviously my 2.73 differential is a factor. I'm not sure how much it matters, but I should have mentioned I have an automatic transmission.
(I know people around here disrespect the auto, but I'm in the Mississippi Delta and autos are great in the mud.)

This gearing may not be optimal for rock crawling, but we have very few rocks here; they're at the bottom of about 1000 feet of mud.
I can get the CJ out on the highway and cruise at 75 with no problem, so I think it's a good compromise given my usage - it spends a lot more time on the slab than in the mud.
But I can get on I-55 and make good time getting to the hunting camp, and still get around once I'm there, so I think it's okay.

Looks like I'll be deciding between the Firestone 31s and the KO 32s.
I'm in the same boat as you. I'm planning on regearing my axles from 2.73 open (D) to a 3.73 and run 32x11.5's on stock rims. I have a T-4. Keep in mind, regearing requires new/different carriers. It won't be a cheap upgrade but at least it'll be done right. I had 31's & 32's on my last CJ with 2.73's and she was a doggggg!

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Unread 01-12-2013, 02:33 PM   #37
Colt44
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I guess if I want to go bigger than 31 I should look into re-gearing.

Just what I need, another project.

What's involved with making that change?
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Unread 01-12-2013, 06:52 PM   #38
Iceman_RNR
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Quote:
Originally Posted by Colt44 View Post
What's involved with making that change?
what's your current set up?
Gearing, transmission ... and have you decided on a tire size?
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Unread 01-12-2013, 07:17 PM   #39
Colt44
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Quote:
Originally Posted by Iceman_RNR View Post
what's your current set up?
Gearing, transmission ... and have you decided on a tire size?
My Jeep came with the 2.73 rear end, so I probably shouldn't go over 31 according to what the folks here are saying. With everything else I've done to this truck, I don't want to get into the rear end just yet.

All the details have been laid out above, but it's the 258 with 4.0 head conversion, MPFI and automatic trans. Plenty of power to do 75 on the highway with no sweat. Just did the YJ spring conversion, hence a couple of inches of additional lift, and the ability to move to bigger tires.
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Unread 01-13-2013, 03:57 AM   #40
Iceman_RNR
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sorry , I totally missed the part about 2.73 gearing ...
To not totally turn it into a dog, 31s would then be better indeed, but at least you know you've still got room to grow
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Unread 01-13-2013, 06:21 AM   #41
keith460
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Yes, with the 2.73 gears, you'll want to limit your diameter to no more than 31". It's not just the diameter that matters when switching to "larger" tires, everyone seems to forget about the added weight that goes along with them. A 33" tire is easily twice as heavy as a factory 29". That's a lot of rolling resistance you need to compensate for with the added expense of re-gearing your axles.
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Unread 01-13-2013, 11:07 AM   #42
Jamesromeos
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32X11.50 on an old 2.5" Rancho Suspension lift. Look great in my opinion, never any rubbing.
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Unread 01-13-2013, 11:42 AM   #43
Iceman_RNR
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currently on mine still 32x11.50

once these are totally worn I'll be stepping up to 33s
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Unread 01-14-2013, 08:27 AM   #44
Colt44
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Just wondering... everybody's been discussing this in terms of manual transmissions, overdrive, etc. - but as I've mentioned, my Jeep has an automatic transmission.
Would that affect things, or be a factor in any way?

Looks like the thread is tapering off, so I want to be sure and thank everybody who responded with such good info.
I knew tire size would have some impact on things, but I didn't realize just how important it was in terms of the whole drive train, from tranny through txfr case to diff to wheels.
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Unread 01-14-2013, 08:42 AM   #45
Matt1981CJ7
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Colt44,

Bare in mind, the advertised and actual diameter of some brands are two different numbers. My BFG 32"/11.50s measured slightly under 31" brand new.

I ran these with my 258/2:73/SR4 setup, and only noticed a small decrease in performance from the previous 31"/10.50s.

Matt
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