Ideal offset/backspacing JL

FreedomRider

Member
First Name
Tony
Joined
Apr 12, 2018
Messages
14
Reaction score
10
Location
Las Vegas
Vehicle(s)
None
is this yr first jeep? I think yr missing my question.
Man, ease up...According to FCA, 35s fit with no backspacing for the standard tire they run on it....Depending on how large of a tire wheel combo, ANYTHING might require backspacingl...You asked a silly open-ended question, and it seems to be getting so typical on these forums...Your question is akin to asking, "Uh, do I need to do a lift to fit larger tires?" How large, how wide, etc, etc, etc...





Advertisement

 

Jammer

Well-Known Member
First Name
Jeff
Joined
Mar 9, 2018
Messages
2,203
Reaction score
528
Location
Ft worth
Vehicle(s)
Bright white JL Rubicon
will -18 fit on a JL with a 37 12.50 17 or 37 13.50 17 ? i know it fits the JK in a 35 12.50 17 I will be running the Mopar 2 inch lift with it which actually lifts it 3 inch
 

aug0211

Well-Known Member
Joined
Feb 19, 2018
Messages
1,519
Reaction score
1,228
Location
Ohio
Vehicle(s)
JLUR Turbo
37s, 8.5 wheel width, 12.5 tire width , 0 offset, 4.5 back space. Sport S stock suspension. In my opinion I’d prefer them to stick out slightly more.
...
...]
Am I mistaken, or does that not match up? 8.5” wheel with 0 offset is not 4.5” BS, is it?

I ask because the wheels I bought are 4.3” BS and I’m nervous about how far 12.5” wide tires will stick out - so I was hoping to use this as a ballpark guide.
 

Jammer

Well-Known Member
First Name
Jeff
Joined
Mar 9, 2018
Messages
2,203
Reaction score
528
Location
Ft worth
Vehicle(s)
Bright white JL Rubicon
I just saw photos of someone's Jeep they sent me and it had-18 offset on the wheels and it was a 10 inch wheel and he put it on a 37 12.50 20 inch wheel and it is not rubbing and fits perfect. I did not think and -18 would work and it does and barely sticks out
 

aug0211

Well-Known Member
Joined
Feb 19, 2018
Messages
1,519
Reaction score
1,228
Location
Ohio
Vehicle(s)
JLUR Turbo
I just saw photos of someone's Jeep they sent me and it had-18 offset on the wheels and it was a 10 inch wheel and he put it on a 37 12.50 20 inch wheel and it is not rubbing and fits perfect. I did not think and -18 would work and it does and barely sticks out
That sounds about right to me, it's a tad over 5" of BS.
 

Lurvis33

Well-Known Member
First Name
Luke
Joined
Dec 1, 2017
Messages
1,586
Reaction score
6,177
Location
Lewisville, TX
Vehicle(s)
‘18 Sting-Gray Sahara
Vehicle Showcase
1
37s, 8.5 wheel width, 12.5 tire width , 0 offset, 4.5 back space. Sport S stock suspension. In my opinion I’d prefer them to stick out slightly more. 466659E9-1A75-470F-A1F1-1DB1BE266D00.jpeg 4D8F95A8-0093-41CB-BC2E-15CEC1394FAC.jpeg 373AE8F9-3453-4616-BB3C-3891B6C18555.jpeg
Are those the 5-127 bolt pattern?
 

TroyBoy

Well-Known Member
First Name
Troy
Joined
Jun 14, 2017
Messages
1,206
Reaction score
1,162
Location
Parksville
Vehicle(s)
2018 JLUR
I just saw photos of someone's Jeep they sent me and it had-18 offset on the wheels and it was a 10 inch wheel and he put it on a 37 12.50 20 inch wheel and it is not rubbing and fits perfect. I did not think and -18 would work and it does and barely sticks out
If you want to know how far out your tires will be then use offset not backspace. Backspace requires you to know the wheel width and offset doesn't.

The simple formula is: Original offset - new offset
So 45mm - (-18)mm = 63mm = 2.5 inches

That 2.5 inches is minimum. You still have to add the extra width of the tire divided by 2. Also, a wider wheel will push out your sidewall a tiny amount.
 

Torero

Well-Known Member
First Name
J. Diego
Joined
Apr 21, 2018
Messages
785
Reaction score
679
Location
Illinois
Vehicle(s)
JL Rubicon, FJ Cruiser, BMW Z3, GTI, F650, MB GL63 AMG
If you want to know how far out your tires will be then use offset not backspace. Backspace requires you to know the wheel width and offset doesn't.

The simple formula is: Original offset - new offset
So 45mm - (-18)mm = 63mm = 2.5 inches

That 2.5 inches is minimum. You still have to add the extra width of the tire divided by 2. Also, a wider wheel will push out your sidewall a tiny amount.
Thanks!!! That’s all I needed. (Actually I only needed the original offset).
 

aug0211

Well-Known Member
Joined
Feb 19, 2018
Messages
1,519
Reaction score
1,228
Location
Ohio
Vehicle(s)
JLUR Turbo
@tmakaro and @Torero -

Careful here... I may be incorrect but I believe we specifically only care about backspacing (BS) and NOT offset if we are trying to figure out how far out the wheels will stick from fenders - for the exact reason mentioned above: offset does not factor in wheel width.

A -18 offset on a 10” wheel ends up looking completely different than the same -18 offset on an 8.5” wheel, for example.

BS takes offset and wheel width into account to give a single measurement that will give you a better idea of how far out you’ll stick.

BS of 4.5” will result in the wheels sticking out the same amount whether that BS is on an 8.5” wheel or 10” wheel. Offset alone doesn’t tell you that.

Others - please correct me if I’m wrong.
 

TroyBoy

Well-Known Member
First Name
Troy
Joined
Jun 14, 2017
Messages
1,206
Reaction score
1,162
Location
Parksville
Vehicle(s)
2018 JLUR
@tmakaro and @Torero -

Careful here... I may be incorrect but I believe we specifically only care about backspacing (BS) and NOT offset if we are trying to figure out how far out the wheels will stick from fenders - for the exact reason mentioned above: offset does not factor in wheel width.

A -18 offset on a 10” wheel ends up looking completely different than the same -18 offset on an 8.5” wheel, for example.

BS takes offset and wheel width into account to give a single measurement that will give you a better idea of how far out you’ll stick.

BS of 4.5” will result in the wheels sticking out the same amount whether that BS is on an 8.5” wheel or 10” wheel. Offset alone doesn’t tell you that.

Others - please correct me if I’m wrong.
Nope. An offset of -18 on a 10" wheel will have the tire stick out exactly the SAME amount as an offset of -18 on a 8.5" wheel. Top tire tread position will be the SAME.

The sidewall will push out more on the 10" wheel but I covered that. I also covered larger tire width.

Edit: The concern is how far out the tire will be not how far out the rim will be.
 

aug0211

Well-Known Member
Joined
Feb 19, 2018
Messages
1,519
Reaction score
1,228
Location
Ohio
Vehicle(s)
JLUR Turbo
Nope. An offset of -18 on a 10" wheel will have the tire stick out exactly the SAME amount as an offset of -18 on a 8.5" wheel. Top tire tread position will be the SAME.

The sidewall will push out more on the 10" wheel but I covered that. I also covered larger tire width.

Edit: The concern is how far out the tire will be not how far out the rim will be.
Interesting - and helpful! Thanks for the correction. I must have misread everything to this point to misunderstand that?

So my tires on 8.5" wheels with -10 offset (4.3" BS) are actually going to be more tucked than the same tires on 10" wheels with -18 offset (4.79" BS)...
 

TroyBoy

Well-Known Member
First Name
Troy
Joined
Jun 14, 2017
Messages
1,206
Reaction score
1,162
Location
Parksville
Vehicle(s)
2018 JLUR
So my tires on 8.5" wheels with -10 offset (4.3" BS) are actually going to be more tucked than the same tires on 10" wheels with -18 offset (4.79" BS)...
When looking at the tire tread only, yes by 8mm. When considering the sidewall, i'm guessing they are probably around the same.
 

matrix311

Well-Known Member
First Name
Eric
Joined
Feb 8, 2018
Messages
101
Reaction score
65
Location
Tempe, AZ
Vehicle(s)
1992 YJ, 2004 TJ, 2008 jKUR, 2018 JLUR (on order)
We have method racing mr312 17x9 wheels wrapped in nitto ridge grapplers 35x12.5R/17. The wheels are -12mm (4.5") backspacing on stock height Rubicon and fit perfect. Not to aggressive sticking out and they clear when the wheel is fully clocked left or right. So far no rubbing that I can see but I have not fork lifted it yet to max flex it out from all sides.

MVIMG_20180514_131136.jpg


MVIMG_20180514_131150.jpg


MVIMG_20180514_131327.jpg
 

boogie

Well-Known Member
First Name
kelly
Joined
Apr 5, 2018
Messages
120
Reaction score
118
Location
70508
Vehicle(s)
jeep jl
We have method racing mr312 17x9 wheels wrapped in nitto ridge grapplers 35x12.5R/17. The wheels are -12mm (4.5") backspacing on stock height Rubicon and fit perfect. Not to aggressive sticking out and they clear when the wheel is fully clocked left or right. So far no rubbing that I can see but I have not fork lifted it yet to max flex it out from all sides.

MVIMG_20180514_131136.jpg


MVIMG_20180514_131150.jpg


MVIMG_20180514_131327.jpg
I just got the same wheels in. Looks great but I think they are 3.5 BS
 

Advertisement




PSC Motorsports
 



Advertisement
Top