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Unread 07-08-2015, 10:01 AM   #1
sk8rgrl
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backspacing question

I have a 97 ZJ with 5" lift on 33x12.5 with 15" rock crawler rims. I just got some free 2015 jk 17" rims. I wanted to put them on with adapters and some 35x12.5 tires that I already have sitting around. I measured the backspacing on these rims and they are whopping 6"!!! My fenders are trimmed front and back but are these rims gonna make it too tight in the front for rubbing stuff? Am I better off with 35's on the 15" rims? I don't wanna have super thick adapters. That seems sketchy to me. are any of you running 17" JK rims? I'd love to see pics or hear opinions on this.

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Unread 07-08-2015, 10:04 AM   #2
DrgnRebrn
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What size are your adapters?
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Unread 07-08-2015, 10:29 AM   #3
sk8rgrl
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Quote:
Originally Posted by DrgnRebrn View Post
What size are your adapters?
I haven't bought them yet but they are 1.25" so it would end up being 4.75" backspacing. Is that still too much? I could get wider spacers but is that a bad idea?
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Unread 07-08-2015, 12:39 PM   #4
kg6mov
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JK rims are 6.25" backspace. So 1.25" adapters only get you to 5".

The final backspace is the thing that matters, so bigger spacers to run deep backspace wheels is no worse (to the wheel bearings, balljoints, etc) than running small spacers on low backspace wheels or no spacers on properly backspaced rims.
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1996 ZJ Green Laredo V8, 2.5" OME and Bilsteins, 33's, Holes drilled in the roof.
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1987 Mercedes 300D Turbo, the diesel daily, 30mpg in style

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Originally Posted by Texas ZJ1 View Post
I heard someone yell "mall crawler" from the back porch. I'll go see who said that. Be right back.
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Unread 07-08-2015, 02:08 PM   #5
Spike6901
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Quote:
Originally Posted by sk8rgrl View Post
I have a 97 ZJ with 5" lift on 33x12.5 with 15" rock crawler rims. I just got some free 2015 jk 17" rims. I wanted to put them on with adapters and some 35x12.5 tires that I already have sitting around. I measured the backspacing on these rims and they are whopping 6"!!! My fenders are trimmed front and back but are these rims gonna make it too tight in the front for rubbing stuff? Am I better off with 35's on the 15" rims? I don't wanna have super thick adapters. That seems sketchy to me. are any of you running 17" JK rims? I'd love to see pics or hear opinions on this.
Isn't the ZJ bolt pattern a 5x4.5 and the JK a 5x5?

The new wheels won't bolt on anyway unless you have already swapped parts or the adapters are accounting for this?
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Unread 07-08-2015, 02:52 PM   #6
PolkaPower
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Quote:
Originally Posted by Spike6901 View Post

Isn't the ZJ bolt pattern a 5x4.5 and the JK a 5x5?

The new wheels won't bolt on anyway unless you have already swapped parts or the adapters are accounting for this?
Wheel adaptors change the lug pattern.
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Unread 07-08-2015, 03:25 PM   #7
kg6mov
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Thats like the point of adapters, to adapt the lug pattern. Otherwise they'd just be spacers.
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1996 ZJ Green Laredo V8, 2.5" OME and Bilsteins, 33's, Holes drilled in the roof.
1998 ZJ Platinum Limited 5.9, Backyard parts fodder
1987 Mercedes 300D Turbo, the diesel daily, 30mpg in style

Quote:
Originally Posted by Texas ZJ1 View Post
I heard someone yell "mall crawler" from the back porch. I'll go see who said that. Be right back.
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Unread 07-08-2015, 04:39 PM   #8
sk8rgrl
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Quote:
Originally Posted by kg6mov View Post
JK rims are 6.25" backspace. So 1.25" adapters only get you to 5".

The final backspace is the thing that matters, so bigger spacers to run deep backspace wheels is no worse (to the wheel bearings, balljoints, etc) than running small spacers on low backspace wheels or no spacers on properly backspaced rims.
This is exactly the info I was looking for thank you. I was worried about thick adapters breaking or breaking something else. The reason I was wanting bigger rims is to eliminate some sidewall exposure. I 4x4 where there is a lot of big pointy rocks and I figured less sidewall showing would mean less chance of a tear or puncture. Maybe I'm crazy but it made sense to me I haven't decided for sure yet. I might just keep the 15" rims and get 35's instead of - adapters, 17" rims on 35's.

"Isn't the ZJ bolt pattern a 5x4.5 and the JK a 5x5? The new wheels won't bolt on anyway unless you have already swapped parts or the adapters are accounting for this?"

I know the lug pattern is different. Hence why I stated in my OP that I was going to use the adapters. They come in different widths.
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Unread 07-08-2015, 04:53 PM   #9
kg6mov
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Check the prices, it may be cheaper to stay at 15", but the price of 17" tires is coming down all the time (because everything ships with them now).

17" also future proofs you for bigger brakes, better steering etc if you find that the 35's are a bit much for stock components.

You're not wrong that less sidewall leaves less exposed, but it also reduces the surface area for the tire to flex when aired down requiring you to stay at higher pressure or risk losing the bead. You also want to consider bashing the rim itself on the rocks instead of the rubber.

Overall for 35's there will still be enough meat left on a 17" wheel to not worry.
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1996 ZJ Green Laredo V8, 2.5" OME and Bilsteins, 33's, Holes drilled in the roof.
1998 ZJ Platinum Limited 5.9, Backyard parts fodder
1987 Mercedes 300D Turbo, the diesel daily, 30mpg in style

Quote:
Originally Posted by Texas ZJ1 View Post
I heard someone yell "mall crawler" from the back porch. I'll go see who said that. Be right back.
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Unread 07-08-2015, 07:08 PM   #10
sk8rgrl
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Quote:
Originally Posted by kg6mov View Post
Check the prices, it may be cheaper to stay at 15", but the price of 17" tires is coming down all the time (because everything ships with them now).

17" also future proofs you for bigger brakes, better steering etc if you find that the 35's are a bit much for stock components.

You're not wrong that less sidewall leaves less exposed, but it also reduces the surface area for the tire to flex when aired down requiring you to stay at higher pressure or risk losing the bead. You also want to consider bashing the rim itself on the rocks instead of the rubber.

Overall for 35's there will still be enough meat left on a 17" wheel to not worry.
Thanks alot for the input. I really appreciate it
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