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Discussion Starter #1
i have a 86 2.5l 4x4 2 door xj with a 4spd stick. anyone know what a 245/75/15 tire is in inches? im lookin to get a set of bigger tires at the junkyard to beat on. i know with certain gears its hard to turn certain tires. i have 215/75/15 on it now. im just tryn to clear some of the bigger rocks on the trails
 

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i have a 86 2.5l 4x4 2 door xj with a 4spd stick. anyone know what a 245/75/15 tire is in inches? im lookin to get a set of bigger tires at the junkyard to beat on. i know with certain gears its hard to turn certain tires. i have 215/75/15 on it now. im just tryn to clear some of the bigger rocks on the trails
What gears do I have and what tires work best? Round ones! :rofl:

Sorry I'm a member of the sarcastic bunch so it had to be said.

There is usually a tag on the diff that will tell you the ratio (you may have to look it up somewhere).

You can get a build sheet from Chrysler. Takes about 3 days, but it's all done over the Internet. (I think this is it http://www.jeep.com/wccsapp/universal/J/index.jsp?appStr=wccs&titleStr=Contact+Jeep&familyStr=brand&franchise=J&actionURL=/wccs/brand_forms/us/webform.jsp&promotion=null&category=U)

You may already know, but the larger the tire and the smaller the diff ratio generally are bad. So first find out the gear ratio you have then you can determine what the best tire diameter for that ratio is.

There are many many tire size to tire size (in inches) calculators, or tables on the Internet. If you can't find out tell me and I'll post some links up for you.

There are also calculators and tables that tell you the best size tires for your gear ratios.

When I decided to go to 32" tires, I looked to see what the best gear ratio would be. I had to read it and decide for myself. I wanted a ratio that would be good on the trails, but still perform well on the highway. It looked like a 4:10 was the best way to go, but I was advised to go one lower, so I went with 4:56 gears.

This is great because even though I turn 3000 rpm at 80 mph my plan WAS to go to 33" tires later, now that I have more experience with the 32s and the height of the rig, I want to go a little higher and a little bigger with the tires.

I'm now thinking about 6.5" of lift and 35" tires. Checking one of those tire size gear ratio tables, I'm still good.
 

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As Mudderoy stated there should be a tag on the diff cover. Look in the lower right corner, should give you the ratio.

I'm betting this has 3:73 ratio being a manual. I also see alot of 3:73's in an auto so... guess it's a crap shoot.

The 4:56 factory ratio was limited to 4 bangers with an AW-4 transmission.... rare.
 

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Discussion Starter #6
ok found the tag now how do i tell which trans i have. are all the 4 speed sticks the same? i gotta clean the tag to read it lol.
by the way im turning 3100rpm at 60mph the 4 wheel shop says i should have a lower gear than 4:10
 

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Discussion Starter #8
I think your trans is a Warner T4.

Did your mechanic means numerically lower (smaller numbers) or lower as in numerically higher?
higher numbers lower gear like 4:25 i think
 

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ok found the tag now how do i tell which trans i have. are all the 4 speed sticks the same? i gotta clean the tag to read it lol.
by the way im turning 3100rpm at 60mph the 4 wheel shop says i should have a lower gear than 4:10
Well maybe that is right for a standard transmission. I have the AW4 with over drive and I turn 3000 rpm at 80 mph. At first glance I'd say 4:10. Look for the tag on the differential, not the transmission.

If you have a digital camera, takes some pics and post them here.

You may have to do what someone else said. Raise the rear rotate the tire/wheel and count how many times the drive shaft turns.

According to the chart, with 30" tires at 65 mph 4:10 or 4:27 for a rpm around 3100 rpm. You're doing 60 (is the speedo corrected) so that would lean towards the 4:27
 

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Discussion Starter #10 (Edited)
hey mudder i can barely read the tag so ill post a pic in sec as soon as i get it loaded


 

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hey mudder i can barely read the tag so ill post a pic in sec as soon as i get it loaded
I'm going to have to send this to CSI for their hollywood magic image enhancements!!! :rofl:

Actually I'll look at it when I get home, I think I can clean it up enough to read it. Someone else may answer the question before that though ;)
 

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Discussion Starter #12
ok i got it now heres what the tag looks like from top to bottom , left to right:)

"4 11 605293-3"
"8953003695 "

now i should figure out which rear it is too. i geuss its a dana?
 

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Discussion Starter #14
4:11 ratio.

I apologise, i earlier said lower right... it's upper left by your description.
so its a dana 35? what other info does the tag provide?
 

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Not sure exactly what the others numbers mean but assume it's build criteria.

Need to see a pic of your differential to be sure but probably a D35 if thats the rear axle. Front would be a D30.

Theres a chart here that ID's axles... i'll see if i can locate it quick.
 

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Discussion Starter #16
Not sure exactly what the others numbers mean but assume it's build criteria.

Need to see a pic of your differential to be sure but probably a D35 if thats the rear axle. Front would be a D30.

Theres a chart here that ID's axles... i'll see if i can locate it quick.
thanks man
 

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Another CherokeeTalk miracle thanks to OverlandXJ. :bow:
 

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Discussion Starter #19
Another CherokeeTalk miracle thanks to OverlandXJ. :bow:
haha yep!
its a 35 no doubt.
whent wheeln tonight, night wheeln popped my front tire off the rim:( used the donught which was flat and my lil compresser sucked. got to a gas station and oiled up the rim and leaned the tire on my other one and got it to pop back on the bead!!!
i picked up my teraflex 1 1/2" front coil spacers for $56 at the local 4x4 place on my way to reiter pit so all in all good day. learned about rears and gears, wheeled, met some jeep guys 2 days in a row, fixed my tire what more do ya need:p
i love this forum by the way!hmm maybe i have to get some stickers,lol
 

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Discussion Starter #20
can a stock xj clear 31's with no lift?i hunted for tires today at the boneyard ALL I FOUND WAS ALOT OF 235/75/15 STUFF and a 30 on a newer jeep rim. im tryn to get a set of 31's from a guy i met out wheeln so im wondering. i have a set of teraflex 1 1/2" coil spacers i just bought but havent installed and the 2.5" blocks in the back on my flat leafs. i picked up some comanche shackles today as well
 
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