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BookspanS

Will The Tires Fit?

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My dad has his factory 32x11's from his JK that he has will work for my factory 2.5. I plan on getting the lug adapters for the 4x4.5 to the 5x5 for the tires. I just need to know will my engine be able to handle the size, and will the factory height need adjustment for fitment? 

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That 2.5 will be gutless without a regear... And unless you want to trim the hell out of your fenders, a lift will be needed to fit that sized tire, especially since the wheel adapters will make them stick out further.

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Thank you. That is exactly what I needed. Approx. what size lift would i need? Would a leaf relocate and 2" lift springs work? Also, referencing a regear, what gear ratio would I need to upgrade to (4.25?)

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Off Topic:  BookspanS, are you still in the Navy?

I am not, sorry :-(. I am still in avaition though working for Boeing in Charleston, SC

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:offtopic:   BookspanS, are you still in the Navy?

I am not, sorry :-(. I am still in avaition though working for Boeing in Charleston, SC

 

 

Okay, that's cool.   :thumbsup:

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Thank you. That is exactly what I needed. Approx. what size lift would i need? Would a leaf relocate and 2" lift springs work? Also, referencing a regear, what gear ratio would I need to upgrade to (4.25?)

 

A 4-5" lift should suffice for that tire size.  By leaf relocate, do you mean converting the rear to spring-over-axle?  If so, that will net you a minimum of 4.5" of lift, but could be as much as 6" of lift.  As far as regearing goes, that is dependent on your transmission and current gear ratio.  If you have the AX4 4-speed, you'll likely have 3.55's.  If you have the AX5 5-speed, you'll likely have 4.10's.  If you have the TF904 3-speed automatic, you could have either 4.10's or 4.56's.  I'm not sure of the exact rule, but I've been told that for every two tire sizes you go up over stock, you want to go numerically up a gear.  So, for instance, stock sized tires are 28's, you want 32's.  If you have 3.55's now, you want to go up to 4.56's.  The stock gear ratios for the axles on our Jeeps go like this, IIRC:

  • 3.07's
  • 3.31's (rare from factory)
  • 3.55's
  • 3.73's
  • 4.10's
  • 4.56's (rare from factory)

Anything above 4.56's and you have to buy some from an aftermarket company. These are available from companies such as G2, Superior Gear, Motive Gear, etc.:

  • 4.56's
  • 4.88's
  • 5.13's
  • 5.38's

Here's some more info on the subject: http://www.alloyusa.com/gear-ratio-calculator/

 

It's should clear up any confusion, but it's not an exact science.  By the way, not all the gear ratios they have listed across the top of their chart are actually available for our Jeeps.

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My dad has his factory 32x11's from his JK that he has will work for my factory 2.5. I plan on getting the lug adapters for the 4x4.5 to the 5x5 for the tires. I just need to know will my engine be able to handle the size, and will the factory height need adjustment for fitment?

They won't fit, and they're much too big for a 2.5L anyway. Let's assume you have 4.10 gears and a five-speed. At 60 MPH, the engine would be turning 2700 in 4th gear, and only 2000 RPM in 5th. That's WAY below the power and torque peaks for the 2.5L.

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Anything above 4.56's and you have to buy some from an aftermarket company. These are available from companies such as G2, Superior Gear, Motive Gear, etc.:

  • 4.56's
  • 4.88's
  • 5.13's
  • 5.38's
It's should clear up any confusion, but it's not an exact science.  By the way, not all the gear ratios they have listed across the top of their chart are actually available for our Jeeps.

 

Last I knew, nobody offered anything steeper than 4.88 for the Dana 30 because beyond that the pinion got so small it was guaranteed to break. So 4.88 is the limit, and there's probably a reason why the factory never offered that as a ratio.

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That 2.5 will be gutless without a regear... And unless you want to trim the hell out of your fenders, a lift will be needed to fit that sized tire, especially since the wheel adapters will make them stick out further.

The stock JK wheels have a deeper backspacing (6.25") than earlier jeeps. With the 1.25" spidertrax spacer adapters I used to run on the XJ the wheels were equivalent to the stock 5" bs wheels.

That said even my 4.0 had trouble turning them with stock gearing until I went to 4.56. With the 2.5 ... 4.88 would be the minimum ratio. 5.13 may prove better but would need axle swaps to accomplish.

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Anything above 4.56's and you have to buy some from an aftermarket company. These are available from companies such as G2, Superior Gear, Motive Gear, etc.:

  • 4.56's
  • 4.88's
  • 5.13's
  • 5.38's
It's should clear up any confusion, but it's not an exact science.  By the way, not all the gear ratios they have listed across the top of their chart are actually available for our Jeeps.

 

Last I knew, nobody offered anything steeper than 4.88 for the Dana 30 because beyond that the pinion got so small it was guaranteed to break. So 4.88 is the limit, and there's probably a reason why the factory never offered that as a ratio.

 

 

While this is true, I was just trying to convey to the OP the different gear ratios that are available to answer his question in more depth.  Based on the chart, anything over 4.88's would require 35" tires or bigger, and so on, to remain optimal for MPG and power, thus leading to the necessity of swapping to stronger axles and making 5.13's, 5.38's, etc. a viable option.  But I do agree that a 4.88's+ in a D30 would not be ideal.

 

But to answer the OP's question, based on the chart (which is just a general idea), I'd say that 4.10's would be optimal for 32" tires.

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He had a 2.5L ... they come stock with 4.10s ... turning 28" tall tires. Put 32s on there and you'll be wanting deeper gears asap. 4.56 is as deep as I'd want to go in a D30 as you're more likely to grenade gears at 4.88. Not even going to mention the D35.

You will most likely he able to live with the stock 4.10s and 32s if you stick to city driving and off road use ... but hit the highway and you're going to lose top gear.

As for the charts ... they weren't designed around 5th gear ... most spec RPM/speeds at 1:1 (4th gear) and the range is usually optimal more for a V8.

 

 

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He had a 2.5L ... they come stock with 4.10s ...

 

That's not necessarily true... His sig says he has an '86 Custom.  I have an '86 Custom that had the 2.5.  It also had the AX4 and my gears are 3.55.  If he has the AX5, then yes he would have 4.10's, TF904 3-speed auto and he could have 4.56's.  The only way to know for sure is to ask... so, BookspanS... what transmission do you have?

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OK, fair enough ... but regardless of what he does have ... anyone that's ever owned a 2.5L can agree that a gear change is needed when going up to 32s. Don't get me wrong, I'm not hating on it ... I loved my 2.5L in my old YJ ... fine motor ... but it's no torque monster or high falootin' powerhouse either.

But to the other part ... will they fit ... with minor trimming yes they will. They will rub the controll arms and in the front and rear lower edges of the wheelwells in the front. But you won't need to get all hacktastic to fit them either. The rear should sqeeze in OK though.

Which again brings us back to making them spin .... bottomline .... the 2.5L is gonna need help.

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I completely agree on the regear as well... The OP could swap in a 4.0 and turning them wouldn't be a big issue, hehe. :brows:   But yea, deeper gears is a must if you wish to go 32's BookspanS.

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i wouldnt recommend it. i have a 88 jeep wrangler with the 2.5/ 5spd and 33" tires. i regeared to 4:88s and it is gutless. you can't get any lower gears for the d30 and probably shouldnt have wasted the money on the d35 lol

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FWIW - my 86 XJ with 2.8/A904 came with 4,10's and I ran 34x9.50 TSL's without much problem... fuel economy suffered though.  Later, I went to 33x12.50 TSL's (only 0.1" shorter) and swapped in 4.56's.  It did better, but then the 2.8 isn't going to impress anyone with it's acceleration abilities.  It's got a few more HP than the 2.5, but the 2.5 has more than that difference in TQ.

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Thank you. That is exactly what I needed. Approx. what size lift would i need? Would a leaf relocate and 2" lift springs work? Also, referencing a regear, what gear ratio would I need to upgrade to (4.25?)

I'm running 31's on aftermarket 15x8's on ny 87 and I rub the leading edge of the front flare when turnjng hard under full compression. I'm currently running ZJ Upcountry coils with an Energy suspensions budget boost. I got a bit over 3" over stock. The rear is stock and clears everything. If you arent afraid of a Sawzall, 32's are doable with 2-2.5". If you want to keep the body stock, I think you'll need to go over 4",I'm afraid.

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You guys have me discouraged now. I got a set of 5 new JK takeoffs for $200 and was planning on running them. My calculations in the past put running 32's with 4:10 gears to be nearly equivalent to having 28's with 3:55 gears. This was according to a chart I saw on here somewhere. I did recently get a set of lower profile tires to put on the JK rims if I was too disappointed by the lack of power of the 32's. I knew 31's will work relatively stock, why would 32's be that much different?

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Depending on the brand, 32's are an inch taller and an inch wider than 31's.  Turning, especially when flexed out, will rub the crap out of the fenders, especially the front, bottom.  Not only there, but the LCA's will get a good rub too.

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Keep in mind not all 32's are created equal. On my ZJ, I ran BFG KO's jn 32 for years with very little rubbing save for thr control arms at full lock. Switched to the KM2's on thr same rims in the same size (on paper) and I hd a lot more rubbing, particularly on the pinch seam and on thr leading edge of my rear fenderwells. I can still spin thr crap out of them, even with a locker and 3.73's. Thank God for strokers. :) What tires are you looking at?

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You guys have me discouraged now. I got a set of 5 new JK takeoffs for $200 and was planning on running them.

AFAIK the smallest wheels on the JK were 16" with a 5" on 5 bolt pattern. Or are you just using the tires?

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The stock Jk 17 inch aluminum rims and Goodyear tires, I think they look like the rubicon Moab style, 5 spoke.

What's the size read on the sidewalls?

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