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Discussion Starter #1
Hello everyone, New JK owner here! Finally got the Jeep after 20+ years of wanting one. Got the fever now and want some tires only problem is, seems like i read some place that 15" rims will not fit on the 08 because of the bigger break disks er... calipers. I want to put some new tires on the jeep but 15" are less than half the price for the 17's. Also, from what i have read i can put on 33's without a lift? Thanks in advance for any help.
 

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33's will fit without a lift. It is only goin to fill the wheel well a bit more then a stock 32" but you might need some bump stops if you are goin to be disconnecting and hitting the trails.

Although, I still think you will end up wanting a bit of lift after you have them on there so you may want to consider that before you make your choice :beer:
 

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No problems here with 15's. Here's when I first took delivery, the dealer put the 15's and 33's on, and then after the 2.5" lift.
 

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Discussion Starter #5
Thanks for the quick response fellas, and the Wheel and Tire thread is awesome! I am ready to sell blood to get some now. You are right, WTF LOL, i want a bit more lift NOW but i will have to wait a bit to afford it. We do a little light offroading and the stock rubber is less than comforting. Again, thanks a bunch guys. I will posting some pics soon as i figure out how.
 

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Discussion Starter #6
That is a good looking jeep John! 2.5" lift...hmmmm
 

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33's will fit without bumpstops but you need 1.25-1.5 less backspacing and they will barely rub in the back. I run 33's with no bumpstop extenders and 2.5 spacers up front and 1.5 spacers in rear. Perfectly level and 35" of articulation measured with a forklift :smokin:
 

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33's will fit without bumpstops but you need 1.25-1.5 less backspacing and they will barely rub in the back. I run 33's with no bumpstop extenders and 2.5 spacers up front and 1.5 spacers in rear. Perfectly level and 35" of articulation measured with a forklift :smokin:
He was asking about with no lift. But still, are you saying that with 33's you can get full "true" compresion (sitting hard on factory stops) with no bumpstop extensions and not rub anywhere in front? Even turning the wheel? I am surprised to hear this.

I know 35's rub, I have 35's with 2 inch bumpstop extensions and still can get them to rub when hard compressed or with momentum. I have not identified exactly where I am getting rubbing so posibly it is on the outer edges (vs top) where the smaller diameter cures it. Otherwise, doing the math (removing 2 inch extension and 2 inch smaller tire) would leave you in the same if not worse situation
 

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Discussion Starter #9
Ok fella's I am bringing it up again! Since the last post I have added a 2" BB. Friday i had my big smile on and cash in hand and went to get my Mojave teflon rims and 35x12.5x15 BFG KM2's Went to 3 tire retailers, one would not sell me 15"s for my 08 because,"THEY WOULD NOT FIT!", another PROMISED me they would not fit, and the third, said no, but he would order 15" steel Rock Crawlers for me anyway. I explainded to all of them that i had seen this set up on my "favorite JK website" I brought up the 4.5 back spacing thing, no one seems to have a clue what I am talking about or how to find out what the BS was. So WTF? Any help brothers...
 

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HI!

If going to tire shops that don't know how to tell what the BS is...go to a REAL tire shop, as these ass-wipes are obviously morons.

A guy at a tire shop who can't figure out your BS is like a carpenter who can't tell a nail from a screw.

:D

So YOU know...the BS can be MEASURED by laying the rim on the ground with the inside facing UP...

1) Lay a straight edge across the open face of the rim

2) Place a ruler with one end on the hub face (Where the rim would bolt to the hub), so that the other end of the ruler up against the straight edge.

3) Look at the distance from the rim's hub face to the straight edge...THAT'S the backspacing of the rim.

:D










Points to Clarify Common Misconceptions:

1) THE OFFSET is NOT calculated like that.

2) The offset is the distance to the hub face from the CENTER of the rim, NOT from its face, etc.

3) The BS is in inches, the Offset is in Millimeters (mm).

4) BECAUSE the BS is measured from the EDGE of the rim, inwards, and the Offset is measured from the Center of the rim to the hub face...you CANNOT subtract one from the rim's NOMINAL WIDTH to get the other.

4) NOMINAL Rim widths (Advertised as an 8" rim for example...) are NOT that TOTAL width...they are measured from ONLY the inner bead areas.

5) A NOMINAL 8" rim for example is really about 9" wide edge to edge....due to the flanges, etc.

6) As the 8" rim is really 9" wide, and the BS is measured from the EDGE...that DIFFERENCE must be accounted for when calculating the BS from the offset.

7) All else being equal, a rim with a given BS will not change its inboard clearance if its wider...BUT the OFFSET CHANGES WITH RIM WIDTH.

SO - lets say I have a NOMINAL 8" rim with ZERO Offset...that means my rim's CENTER is 4.5" in from either edge, and zero inches off from my hub face (Its centered).

Your stock rims have 6.25" of BS...so 4.5" of BS is 1.75" less BS for zero offset...on an 8" nominal rim size.

And so forth.

So if getting new rims for 35 x 12.5 tires, and they will be 8" nominal sized rims, and you want at least 1.5" LESS BS (3.75" to 4.75" of BS...)...

...that's ~ close to the zero offset position

:D

Hope that helps!
 

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Had the same problem a while back when I was trying to get some wheels and tires for my Dakota. The morons tried to tell me that they wouldn't fit. I told them they would and that I wanted them weather they thought they would fit or not. One place wouldn't sell them to me and another strongly discouraged the sell. I finally to them to shut up and take the money or I would take my business elsewhere. They decided that it WAS my decision and my money and sold me what I asked for. Remember most of these places are run by idiots that only know what the computer in front of them tells them. :pissed:
 

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2.5"

That is a good looking jeep John! 2.5" lift...hmmmm
You should shop for a deal. I got my 2.5 BB lift for $226.00 with free shipping. My Wife and I installed it in the Drveway on a Satruday. Not bad for 2 old people! :grinpimp:
 

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Discussion Starter #13
TEEJ, you are a wealth of information. That helps tremendously! I knew they guys were incompetent when I had to explain to them how to calculate aspect ratio “Hey pal, you work in a TIRE STORE.” Now I will have to return to the store and give a class I suppose. Would have never thought that it would be this difficult to buy a freaking tire and rim.
Even briefly thought about forcing the sale but considering I was about to drop 1500 bones I started to second guess the things I had read. Thanks again fellas for all the help!
 

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Discussion Starter #14
Feel like i am beating a dead horse here! Well it turns out the sales “kids” were right. After talking to American Racing's customer service the Mojave’s, or any of the others I liked, comes in a 5x5 in a 15” I have actually found very few rims in 5x5 in a 15” WTF? Would it be advisable to get the adapters that switch 5x5’s to 5x4-1/2? Thanks again for all the help...:beer:
 

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Discussion Starter #16
Well the tires are much more inexpensive, on the KM2’s it is right at $100 per tire. If I go to a 15" tire I can almost get the rims for nothing. Not to mention replacing them in less than 40K miles. It seems like I might have to settle for 17’s though. Just out of curiosity what do you feel are the advantages to the 17’s?
 

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I have been wheeling for over 20 years and had more than 10 Jeeps and 17 wheeling rigs.

For years 4 wheelers got used to their 15" wheels and airing down to get more tire on the rocks off road. The problem is that at some point you loose efficiency and the tire folds back in on itself and you are no longer trying to get a round object over a rock, but a square one.

A larger inner circle helps to keep the "roundness" of the tire while still allowing you to air down to a point of traction.

I have been running 17" tires on a Jeep for about 6-7 years. (was one of the first). The TJ I ran them on climbed better and side hilled better.


Keep in mind that when 15s were really popular 33" tires were considered huge. :laugh:. Now it is very common to see 37s on daily driven Jeeps.

Back in the day a 33" tire on a 15" wheel left you with a 9" sidewall. A 35" tire on a 17" wheel gives the same 9" sidewall.

Factory Rubi wheels were a 32" tire on 17" wheel which is a 7" sidewall. Less sidewall translates to better handling on and off road. (go find a Jeep with 37s on it and move the steering wheel with the Jeep parked. You will see the Wheel move inches before the tire even begins to respond. :eek:).

So by going to a 15"/16" wheel you get sloppier/less responsive steering, more tire swat and squirm under braking, worse sidehilling ability, and potentially a tire that folds in on itself off road to create more stress on your components as you try to force a square object over rocks..

EDIT: (just so you don't have to do the math. an 18" with a 35 is 8.5" of sidewall, a mere 0.5" less sidewall than the beloved 33 on a 15" wheel, 37s would put that at 9.5" of sidewall. )



Here is a pictures of Clifton's Poinson Spyder JK. Guess what? Those are 18's:wave:

 

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Discussion Starter #18
Thanks bro. You make a very compelling argument. That was one of the concerns I had, on road performance. The wife drives it during the week, only about 10 miles a day, but… I have had lifted trucks with “sloppy” tires in the past and it can get interesting especially in the rain. We wheel it just about every weekend, was looking for a happy medium, guess thats it.

So basically, suck it up spend the extra 400 bones and reap the benefits…? :beer:
 

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In my opinion there really is no other choice. I was amazed when I did them on the TJ. Just an all around better performer. FWIW I run 17s on the JK, the TJ and on my 1 ton truck with 37s.
 
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