Backspacing difference

[Clint in KY]

I am in search of steel wheels for my 2003 Liberty Sport. I got the specs for stock wheels and am doing some comparisons. I found a Crager D342 with all the proper numbers - BUT - the backspacing is 4" rather than the stock 5.5".

As I understand backspacing, the Cragers would stick 1.5" farther out (measured to the outside of the rim) than a stock wheel. I know from my Honda days that if you go too far out the wheel bearings are unevenly loaded and will fail at a rate commensurate with the amount the wheel is out from stock.

I wouldn't mind a bit wider stance but not if it means the suspension will suffer for it. Are these feasible wheels for my Liberty?

 

[TwoBobsKJ]

I am in search of steel wheels for my 2003 Liberty Sport. I got the specs for stock wheels and am doing some comparisons. I found a Crager D342 with all the proper numbers - BUT - the backspacing is 4" rather than the stock 5.5".

As I understand backspacing, the Cragers would stick 1.5" farther out (measured to the outside of the rim) than a stock wheel. I know from my Honda days that if you go too far out the wheel bearings are unevenly loaded and will fail at a rate commensurate with the amount the wheel is out from stock.

I wouldn't mind a bit wider stance but not if it means the suspension will suffer for it. Are these feasible wheels for my Liberty?

Don't worry about the wheel bearings - that's not a serious concern with the Liberty's suspension. The challenge with that backspacing is the rubbing you're likely to get on the inner fenders - unless you're lifting the Jeep too. With the wider arc described by the reduced backspacing you'll hit parts of the inner fender that are cleared with your current stock wheels. The problem can be corrected with some trimming and pounding down the pinch weld at the rear of each front wheel well; if you're willing to put up with the rubbing or pushing some of the plastic liner out of the way those wheels will certainly work. And it does give the Libby a nice aggressive stance arty52:

Is a lift or new springs/shocks in the picture?

Bob

 

[Clint in KY]

Don't worry about the wheel bearings - that's not a serious concern with the Liberty's suspension. The challenge with that backspacing is the rubbing you're likely to get on the inner fenders - unless you're lifting the Jeep too. With the wider arc described by the reduced backspacing you'll hit parts of the inner fender that are cleared with your current stock wheels. The problem can be corrected with some trimming and pounding down the pinch weld at the rear of each front wheel well; if you're willing to put up with the rubbing or pushing some of the plastic liner out of the way those wheels will certainly work. And it does give the Libby a nice aggressive stance arty52:

Is a lift or new springs/shocks in the picture?

Bob

To answer your last question = not likely.

I am confused. Why would moving a wheel OUT cause it to interfere with the inner fender well?

Am I incorrect that a 4" backspacing will make the wheel stick farther OUT than a 5.5" backspacing? Would not the inner surface of the wheel be farther away from the inner fender well? I could see the problem where the wheels tucked into the fender well as on a sedan. This was a problem on Hondas that that were lowered which made them either roll the fender well edges out or actually stretch the fenders out to get the clearance needed.

As my Liberty sits now, with its 15 year old suspension sag, the entire top of the tire is still well below the wheel well arch.

 

[TwoBobsKJ]

To answer your last question = not likely.

I am confused. Why would moving a wheel OUT cause it to interfere with the inner fender well?

Am I incorrect that a 4" backspacing will make the wheel stick farther OUT than a 5.5" backspacing? Would not the inner surface of the wheel be farther away from the inner fender well? I could see the problem where the wheels tucked into the fender well as on a sedan. This was a problem on Hondas that that were lowered which made them either roll the fender well edges out or actually stretch the fenders out to get the clearance needed.

As my Liberty sits now, with its 15 year old suspension sag, the entire top of the tire is still well below the wheel well arch.

Yes, the 4 inch backspacing will move the wheels further away from the center of the Jeep; the stance will be wider than stock. If the front wheels are straight there won't be any interference. But when the wheels are turned to go around a corner, then the problem shows up.

It's difficult to explain with just words - pictures would help. But do this...

Grab the end of a pencil or pen while holding it flat on your table. With the thumb and first finger on your other hand, "pivot" the pen back and forth along the table and observe the arc your thumb and finger trace along the table. Maybe even place a mark or other object on the table along the line the arc traces; imagine your thumb and finger represent your stock wheel and that the wheel clears the inner fender.

Now, move your thumb and finger to the end of the pen, opposite the end that's holding the pen; this represents the wheel with less backspace that moves the wheel further out away from the center of the Jeep. Move the pen back and forth and notice the new, wider arc described by your thumb and finger on the end of the pen. See how the wider arc 'hits' the imaginary inner wheel well? That's what happens when you decrease the backspace on new wheels compared to stock. The arc is widened and the tire will hit portions of the wheel well and/or suspension that it didn't hit before.

I'm sure there's a graphic somewhere out here on the inter web but I'm too lazy to look for it. The exercise above can be done with a high school geometry compass if you have one laying around. Trace an arc with the compass opened up an inch or so, then widen the arc to 1.5" - the idea is the same.

Hope this helps :shrug:

Bob

 

[Clint in KY]

As I understand backspacing, the Cragers would stick 1.5" farther out (measured to the outside of the rim) than a stock wheel.

This is where I went awry. A wheel with LESS backspacing, such as the Cragers with 4" instead of 5.5" will make the wheel stick farther IN not OUT. In which case, yes I see the problem.

So for a wider stance with the same width wheels I would need to find a wheel with MORE backspacing. Not likely as all I have seen is 5.5" on stock wheels (my first option) and 4" & 4.5".

I think I will go with my first instinct and find some factory steel wheels and have them powder painted.

 

[tommudd]

BACKSPACING 101

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In the last picture imagine that is with stock 5 inch of backspacing ( picture to the left) and the one on the far right is with 4 inches of backspacing
You cant go much more than 5 inches of back spacing on a KJ nor would you want to.
On a non lifted KJ you have to stay at stock due to the arc the wheel travels in like Bob mentioned. The farther out you are the more its going to rub, front and rear part of the front wheel liner

 

[tommudd]

This is where I went awry. A wheel with LESS backspacing, such as the Cragers with 4" instead of 5.5" will make the wheel stick farther IN not OUT. In which case, yes I see the problem.

So for a wider stance with the same width wheels I would need to find a wheel with MORE backspacing. Not likely as all I have seen is 5.5" on stock wheels (my first option) and 4" & 4.5".

I think I will go with my first instinct and find some factory steel wheels and have them powder painted.

For a wheel to stick farther out you would need less backspacing not more, 4 inches -vs- 5 inches
But in the end, unlifted you are pretty much stuck ( well technically you are) with stock backspacing of 5 inches

 

[TwoBobsKJ]

This is where I went awry. A wheel with LESS backspacing, such as the Cragers with 4" instead of 5.5" will make the wheel stick farther IN not OUT. In which case, yes I see the problem.

So for a wider stance with the same width wheels I would need to find a wheel with MORE backspacing. Not likely as all I have seen is 5.5" on stock wheels (my first option) and 4" & 4.5".

I think I will go with my first instinct and find some factory steel wheels and have them powder painted.

Nope, you have it backwards.

A wheel with less backspacing - 4" vs 5.5" - will stick further OUT, away from the center of the vehicle.

The operative word is "back" - spacing. With MORE backspacing the wheel will be moved "back" in to the center of the vehicle. LESS backspacing will mean the wheel is less "back" and so it will stick out more. Kinda confusing, isn't it? :ROFLJest:

So, to clarify. The Cragar wheel with 4" of backspacing will be 1.5" less "back" than a stock wheel at 5.5" so it will protrude 1.5" further out away from the center of the Jeep. In other words, with Cragar wheels on both sides of the Jeep the track will be three inches wider overall (1.5" on each side.)

Clear as mud now...? :icon_lol:

EDIT: Just saw that Tom was posting as I was writing this. Wish I had the pics like Tom does - makes it so much easier to explain and communicate.

Bob

 

[tommudd]

Hi Bob
Do we have him totally confused now and shaking his head? :shrug:

:happy175::ROFLJest::gr_grin:

 

[Clint in KY]

I see what you are saying but I am finding conflicting information.
In the picture below it clearly states that less backspace moves the wheel outward (left example) and more backspace moves the wheel inward (right example), which was my original understanding. I am not seeing how moving the wheel outward could cause it to get closer to the inner surfaces which would cause rubbing.

 

[tommudd]

I see what you are saying but I am finding conflicting information.
In the picture below it clearly states that less backspace moves the wheel outward (left example) and more backspace moves the wheel inward (right example), which was my original understanding. I am not seeing how moving the wheel outward could cause it to get closer to the inner surfaces which would cause rubbing.

LOL OK as you move the wheel out away from the vehicle the arc in which it travels increases ( wider arc)
So the more the wheel sits out, the more it is going to hit
Trust us most of us have been playing with 4X$s for years, with KJs last 12 years so we've seen and tried most everything there is. Unlifted with say 4 inches of backspacing you are going to rub and rub bad, especially when sagged as well

 

[tommudd]

Go out and bungy strap a piece of 2x4 to your wheel ( straight across) on the out side (same length) as the diameter of your tire, NOW start turning the wheel back and forth all the way
You''ll soon see what we mean

 

[TwoBobsKJ]

Hi Bob
Do we have him totally confused now and shaking his head? :shrug:

:happy175::ROFLJest::gr_grin:

I see what you are saying but I am finding conflicting information.
In the picture below it clearly states that less backspace moves the wheel outward (left example) and more backspace moves the wheel inward (right example), which was my original understanding. I am not seeing how moving the wheel outward could cause it to get closer to the inner surfaces which would cause rubbing.

Shoot Tom, now I'M getting confused :ROFLJest:

Clint, that example is saying the same thing Tom and I said. Less backspace moves the wheel out, more backspace moves the wheel in. Four inches is less "back" than five inches - so the wheel is moved outward.

Again, moving the wheel out increases the length of the arc the wheel must travel to go from lock-to-lock when turning. A wider arc - on a wheel with less backspacing - will cause the tire to hit the inner fender liner on the Liberty when you turn the wheel.

Another example: A doorway in your house has a 32" door - it fits just fine and closes and latches just fine. Imagine if you put a 34 or 36 inch door in a doorway that is only 32 inches wide; the door would hit the door jamb and wouldn't close. The arc the wider door must travel is longer (wider) than the door frame can fit. The same thing happens when you use wheels that widen the stance of your Jeep - the tires have a wider stance (like the wider door) and will hit the inner wheel liner (the door jamb) and you'll have interference.

Do the exercise I described above with a pen or compass. You'll be able to trace the arc and see exactly where the tire will hit the wheel well.

Bob

 

[tommudd]

Door example is good
I am about ready to head to the garage with a 2x4 and the camera

 

[dude1116]

So here's how I see it. These are very rough sketches of what I believe happens. Imagine this is a top down view of your tire (through the upper fender/fender flare) and a side view of your wheel.

The way our fender liner is shaped really causes the issue. As you move the tire OUT, the outward edge of the tire gets closer to the closer part of the fender liner. That's how it hits. If we had a more linear/flat fender liner, the backspacing wouldn't make AS MUCH OF a difference.

With the outer edge of the tire going out more, you have to imagine you're moving the whole line of travel (which is a semicircle) outward. I drew part of that line of travel as an arrow in my first picture.

When you are unlifted, the CENTER of the tire (which has a longer length across) is closer to the closest part of the fender liner (towards the bottom of the fender). When lifted, the length of that line across the tire (even with the bottom of the fender liner) is reduced (with the same size tire), allowing you to modify your Jeep to have less backspacing/bigger tires/wider wheels.

I hope these help! I know they're crude drawings but i think i got the point across!

EDIT: My first picture is referring to the FRONT fender (which is also a problem...my problem currently). Same concept applies to the back.

 

[Clint in KY]

Nope, you have it backwards.

A wheel with less backspacing - 4" vs 5.5" - will stick further OUT, away from the center of the vehicle.

The operative word is "back" - spacing. With MORE backspacing the wheel will be moved "back" in to the center of the vehicle. LESS backspacing will mean the wheel is less "back" and so it will stick out more. Kinda confusing, isn't it? :ROFLJest:

So, to clarify. The Cragar wheel with 4" of backspacing will be 1.5" less "back" than a stock wheel at 5.5" so it will protrude 1.5" further out away from the center of the Jeep. In other words, with Cragar wheels on both sides of the Jeep the track will be three inches wider overall (1.5" on each side.)

Bob

So how does moving the wheel out cause rubbing? This is the part that I am not seeing.

 

[tommudd]

You can see in the first picture the wheel and tire have enough room to turn

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NOW with just a 1 inch wide yard stick held up to show backspacing of 4 inches instead of 5 you can see that it would hit before you could fully turn

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[tommudd]

So how does moving the wheel out cause rubbing? This is the part that I am not seeing.

Because the wheelwells are small!
Only enough room to have stock backspacing
Its...........................

 

[Clint in KY]

I think I know what piece of information I am missing.

What part of the tire is going to rub what part of the vehicle?

The 2X4 reference made me wonder if I were to strap a 1.2" (the difference in the wheels) slat with the same length as the diameter of tire to the outside of the tire, what would it hit. My answer to myself was "Nothing" as the tire has room in front, in back and on top in the wheel arch far in excess of that 1.5".

 

[tommudd]

I think I know what piece of information I am missing.

What part of the tire is going to rub what part of the vehicle?

The 2X4 reference made me wonder if I were to strap a 1.2" (the difference in the wheels) slat with the same length as the diameter of tire to the outside of the tire, what would it hit. My answer to myself was "Nothing" as the tire has room in front, in back and on top in the wheel arch far in excess of that 1.5".

Your answer to yourself was wrong, totally wrong
With stock wheels yes you would be correct , not with 4 inch backspacing, it will hit front and rear both

We don't make these things up just for the heck of it ya know:happy175:
What we are telling you is the truth and nothing but the truth