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Old 08-16-2017, 09:15 PM
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Wheel dimensions... confusion and frustration.

Good evening all.

I come once again to drink from the well of JEEP knowledge. I have a 2015 JKU-R Hard Rock, color is Copper Brown. I am slowly building it into what I want it to be. This December I will be adding an AEV 2.5 inch lift. This lift is so that I can put a set of BFG KO2s under it. I run mostly sand-rock-desert.

What I am struggling with is wheels. There are hundreds of wheels out there. But the numbers and advice all gets confusing. I have tried asking questions of a few manufacturers, only to get an almost boilerplate reply that says "Just buy our wheels, guaranteed to fit." But they all have different numbers. And I suck at math! Here is an example.

One very popular, well known and respected company has several wheels that are known for quality, and I have seen them often on exactly my JEEP with exactly the tire I want. But they only come in one color (black), and they are very expensive. The specs are this.

Diameter=17". Width=8.5". Backspace=5.2". Offset= +10mm.

A friend who works in a well-known nationwide tire shop owes me a big favor - I did some electrical work on a 60s T-bird for him. He can get me some REALLY NICE wheels - in a Bronze color that will match my Hard Rock. At a significant discount over list price. The trouble is, while he says they will fit perfect, the specs don't quite match the well-known company specs. The specs are:

Diameter=17". Width=8.5". Backspace=4.75". Offset= 0.0mm.

Now, this is where I get to thinking.... and thinking can be a VERY DANGEROUS thing without knowledge or experience to back it up. But here we go. The difference in the backspacing of the 2 different wheels is 5.2" - 4.75" = 0.45". The difference in offset is 10mm. It just so happens that 0.45" inches is 11.43mm. Almost 10mm. So if I am reading this right, removing the 10mm offset will also allow the backspace to Change by 0.45 inches?

Using this information, a Positive (+) offset looks like it would require the backspacing to be less.
https://www.4wheelparts.com/tire-whe...ckspacing.aspx

I am so confused. Perhaps I should just suck it up, buy the expensive but well-known black wheels and be done with it?

Can someone point me to a web page that can explain it all in such a way that I can understand it? Or perhaps confirm that I have it figured out after all? THANKS VERY MUCH !!!!!

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Old 08-16-2017, 09:28 PM   #2
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The lower the backspace number the further it pushes the tires out away from the jeep. Which is what you need. 4.75” backspacing move the tires away from the jeep by .45” more than the one with 5.2”.

Another way to say it, the 4.75” backspacing will have less clearance issues with bigger tires than the wheel with 5.2”.

Depending on tire size, 5.2” may be plenty. The bigger you go with tires the lower the number of backspacing you need.

For comparison, the stock wheels are 6.25” backspacing.

Hope this helps


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Old 08-16-2017, 09:38 PM   #3
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But, the width of the wheel factors in also.
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Old 08-16-2017, 09:45 PM   #4
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^^^These charts should help you to understand.

Wheel Rim width and Back Spacing is what you need to look at.

Most on the Forum that run 33's, 35's, or 37's..Go with 8.5" to 9.0" width, along with 5.0 to 4.5 Back Spacing.

A real popular size on this Forum is a 9" wide Rim width, with a 4.5 Back Spacing..FYI
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Old 08-16-2017, 10:10 PM   #5
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Ignore offset as it is effectively irrelevant on a Jeep.

You want between 5.2 and 4.5 back spacing and a wheel width from 8 to 9 inches. Any combination there is fully functional on a JK. The 5.2's are tucked in pretty tight... I run 4.75 on a 9 inch wheel and they are a great fit.

Wheel width is not a factor if it's in the desired range.
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Old 08-16-2017, 10:35 PM   #6
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/\This [\thread]

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Old 08-16-2017, 10:47 PM   #7
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Another factor is the lug spacing. The Jeep YJ and TJ used 5 on 4.5 (that means 5 lugs on a circle that is 4.5" in diameter. The JK/JKU uses 5 on 5 (which means 5 lugs on a circle 5" in diameter. (Also referred to a bolt pattern).

Choosing the wheel will also have an effect on tire choice. Some tires you like might not be available in the size you want. And a different diameter wheel may cost or save you money.

For example, let's suppose you want to run a 35" BFGoodrich A/T KO2 tire, a tire and a size that is very popular. So, you search the BFG website for 35/12.50R16 because you want more rubber and less wheel when off road. Uh Oh. BFG says they do not produce a tire in that size. So you go back in and search the site for 35/12.50R17 and get the same result. Not manufactured in that size.

But you know Jeepers who are running 35" BFG KO2s. So you go back in and search for 35/12.50R18 tires and bingo they make them in that size. But they want $354 per tire. To translate the spec, it is a tire that is approximately 35" tall, is approximately 12.50 wide at the widest and fits on an 18" diameter wheel. For the tire, backspace does not matter but wheel width does and the manufacturers tell you the range of wheel width to choose - in this case 8.5" to 11".

Also remember that 35" is the class of tire. The actual dimension (according to BFG) is 34.53". But you distinctly heard the one Jeeper mention what a good price he got on 35" BFG KO2s that fit his 16" wheels.

So you dig deeper into the KO2 specs and find a tire that is 34.41 inches tall, but it is called a 315/70R17. Meaning it is a 315 mm wide tire with a height to width ratio of 70 percent and fits on a 17" wheel. The tire is 34.41" tall very close to the first tire, but is a bit wider at 12.72", but it is only $302 a tire. If you are buying five that is a savings of $260 for the set.

But then you notice a 315/75R16 tire that is 34.57 inches tall, but is only 12.32 inches wide, but wow, they are only $261 a tire. A savings of $465 a set of five. That would pay for a couple of the wheels.

So, search, compare and search again. Balance wheel availability and tire availability against cost. Most JK Jeeps will be running 17" wheels, a few 16" and a very few 15". There is an issue of clearing the brake caliper on some alloy 15" wheels, but 15" steel wheels should clear. There are also a few who run 18" because that's what came on their Sahara.

If you are in data overload by about now, don't worry, that is normal. The combination of tires and wheels available from manufacturers is easily up into the tens of thousands. As stated, start with your wheels. Are they available in both 16" and 17" sizes? Both with the 4.75" back space and 5 on 5" bolt pattern? If so that gives you a lot of flexibility in tires. In the BF Goodrich tires for example the Mud Terrain KMs that are on the Rubicons and my Chief are not available in all sizes, but there is also a KM2 line that has different sizes. I don't know if BFG is phasing out the KMs and going to the KM2s or not.
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Old 08-16-2017, 10:49 PM   #8
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I'd rather have the 5.2 +10 cause the law is strict around here on how far the tires stick out.
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Old 08-16-2017, 10:55 PM   #9
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37x12.5r17 Goodyear mtr/17x8.5 method hole wheels with 4.75 backspacing.


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Old 08-16-2017, 11:10 PM   #10
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Wheel dimensions... confusion and frustration.

Quote:
Originally Posted by Mrfallon View Post
37x12.5r17 Goodyear mtr/17x8.5 method hole wheels with 4.75 backspacing.


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My buddy has 4.5" backspaced wheels with 12.5" wide tires and stock fenders,I think it looks like it's on roller skates!....anymore than 4.75 and I think you'll need flat fenders with 12.5" wide tires or it may look like it's on roller skates?clearance problems are also because of the lift sticking out/not just frame etc...I put my stock wheels back on for fear of my jeep being too tall to leave my garage and it wouldn't move as my new lift was wedged against my stock wheels 6.25 backspacing(luckily I was just low enough and didn't have to let air out of my new 37's to exit the garage).i was also confused when wheel shopping but if you're going with a 12.5" wide tire...the minimum I would run would be 4.75 backspacing...mine is perfect at 4.75 for me.just think a lot of people keep the stock rubicon wheels with 6.25 backspacing and add 1.5" wheel spacers which equals 4.75 so that's how you know it works/is the perfect size!just search jeep images and when you find the perfect look/stance....ask the owner all their specs(wheels/tires/lift).


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Old 08-20-2017, 12:58 PM
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OK - and yes - information overload. I get this at work all the time. I am one of about 5000 people certified to run the power grid. We receive constant training..... and sometimes it is like trying to drink water out of a fire hose. <grin>.

In my Initial Post I wrote:

One very popular, well known and respected company has several wheels that are known for quality, and I have seen them often on exactly my JEEP with exactly the tire I want. But they only come in one color (black), and they are very expensive.

The specs are this. Diameter=17". Width=8.5". Backspace=5.2". Offset= +10mm.


These wheels are the AEV Pintlers. And after talking to my wife (who wants BLACK wheels on her side of the JEEP) I am actually leaning this way. Can anyone say anything bad about the way AEV wheels fit or look?

I also wrote:

A friend who works in a well-known nationwide tire shop owes me a big favor. He can get me some REALLY NICE wheels - in a Bronze color that will match my Hard Rock. At a significant discount over list price. The trouble is, while he says they will fit perfect, the specs don't quite match the well-known company specs. The specs are:

Diameter=17". Width=8.5". Backspace=4.75". Offset= 0.0mm.


These wheels would be the Method Con-6:
https://www.methodracewheels.com/pro...lack-steet-loc

So here is the bottom line. The AEV 2.5" lift with the Geometry Correction Brackets, 5 35x12.5/17 BFG KO2s, and wheels of any kind is already over budget. But I'll find a way.

My buddy can sell me 5 of the Method-6 wheels for $225 less than the AEV wheels will cost. Thanks to all of you, it looks like the Method Con-6 will fit. I have not been able to learn much about their strength. AEV says their wheels are totally safe with tires up to 37 inches.

Now, here is the final piece to the puzzle. When I retired from the Army and got this really fantastic job, my wife sort of semi-retired. I was fine with that. She trains dogs and makes a few bucks doing dog classes and writing web pages for dog breeders. But in order to facilitate all of my JEEP work, she informed me last night that she is taking on a part-time job to help pay for whatever wheels I want..... just as long as the wheels on her side of the JEEP are BLACK.

Hell - what do I do now? I guess if you MUST have a problem, this isn't a bad one to have.

THANKS everyone for the input and advice. I learned a lot (as I always do from you guys). I am a the moment leaning toward the AEV Pintlers - in Black.

Do you want to hear the final kicker? For our 40th anniversary next year, she wants me to take her on a 5-day guided expedition through the Gila Wilderness. Did I get lucky 40 years ago or what?

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