I"ll ask again.....lowers- wheel offset- tire size

[Jeep Driver]

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I'm currently running 31s with WJ lowers.

 

I'm about to install adjustable lowers and order new wheels.

 

New tire size will be 285/60/18 on 18x9 wheels.

I'm looking for the correct offset or back spacing. Main concern is rubbing on the lowers or rubbing the swaybar or any other interference with the new tire size.

 

Your thoughts will be appreciated.

[HOrnbrod]

18x9 wheels.

 

Have you picked out your wheels yet? What is the offset - BS specs for these? Same bolt pattern or will you be using adapters? I'm thinking of doing this also using 18" JK wheels.

 

Tire height should not be a concern since most street 31" tires are near 31" and tires that fit 17" and 18" wheels are only about 1" to 1-1/2" taller. As compared to JK wheels / tires.

[Jeep Driver]

No, that's just it........I'll having a hard time deciding on which wheel.

 

Yes, same bolt pattern, 5x4.5

 

Aftermarket, probably Fuel or something similar.

 

 

Problem is everything has to be ordered, it's not like I can pick one and measure it for backspacing.

 

And depending on the site.....numbers conflict with other sites......offset vs backspacing.

[Jeep Driver]

Oh, BTW....

 

Local tire dealer did get in one Nitto 285 for me........10" of tread width, lots of meat on this tire and that's why I'm concerned with the right wheels.

[HOrnbrod]

Thought you had already decided on wheels. Obviously you have to choose, then call the mfg. for the wheel specs and go from there. 10" of tread doesn't allow much wiggle room w/o slashing and hacking. But of course you know that. Good luck.

[kansashogan]

 

http://www.tirerack.com/wheels/results.jsp?autoMake=Jeep&autoModel=Comanche+Pick-up&autoYear=1988&autoModClar=&package=false

This might help. Might not. But you could call them and I bet they could help.

[Jeep Driver]

 

 

http://www.tirerack.com/wheels/results.jsp?autoMake=Jeep&autoModel=Comanche+Pick-up&autoYear=1988&autoModClar=&package=false

This might help. Might not. But you could call them and I bet they could help.

 

 

 

 

Thanks, but sites like this keep you in a box.......I don't like to be in a box.

[gogmorgo]

It's not too difficult to calculate back spacing from offset. Just divide the overall width of the wheel by two and then add the offset.

Offset is the distance between the mounting surface and the centreline of the wheel. A positive offset is where the mounting surface is closer to the outside of the wheel, and a negative offset is closer to the inside.

A 9" wide wheel with a -1.5" offset will have 4.5 + -1.5 = 3" backspacing. A 10" wide wheel with a +2" offset will have 5 + 2 = 7" backspacing.

[Megadan]

An even simpler way from ^ is to simply remember that offset is a value in MM from the centerline of the wheel, with positive being toward the face side, negative toward the back tire mounting surface.  Backspace is the distance from the wheel mount surface to the back edge of the wheel.

.  Since the offset is 0, it is exactly at the centerline of the wheel, thus half the wheel width from the mounting surface to the back edge of the wheel.  
EDITED

[Jeep Driver]

Here is the conflicting information- http://www.ebay.com/itm/Vision-Off-Raod-372-Raptor-18-18x9-5-5x114-3-18mm-Black-Machined-Wheels-Rims-/301391557690?fits=Make%3AJeep&hash=item462c56343a&vxp=mtr

 

 

 

 

Wheel- 9.5 inches

center is 4.75

offset is +18 or .70"

 

Doing math- back 4.75 + .70 is 5.45

 

They list the backspacing at 6"

 

 

 

What am I missing?

 

 

Edit:

 

Is the 1/2" difference the distance between the inside of the wheel where the tire bead is and the outside of the rim?

[Megadan]

Well, there are factors that can throw the numbers off and make it a lot less cut and dry.  One big one is that offset is the centerline in relation to the actual lip that the tire bead mounts to (Wheel flange), and backspace measures from the very back edge of the wheel lip to the face of the wheel.  This means that it is not quite a direct transaction.  an et+18 on a 9.5" wheel width does roughly equate to a 6" backspace. (5.9xx) 

The math to find backspacing from rim width and offset is as follows:
Step 1.  Add 1" to the rim width to account for the wheel flanges.
Step 2. Divide by 2 to find wheel centerline.
Step 3: Convert the offset to inches. Add to centerline measurement if offset is positive, subtract if negative.

Thus. 9.5 width +1" = 10.5"
10.5/2 = 5.25"
18mm / 25.4 = .708"
5.25+.708 = 5.958" backspace

Hopefully that clears it up a bit.

 

[Jeep Driver]

Well, there are factors that can throw the numbers off and make it a lot less cut and dry.  One big one is that offset is the centerline in relation to the actual lip that the tire bead mounts to (Wheel flange), and backspace measures from the very back edge of the wheel lip to the face of the wheel.  This means that it is not quite a direct transaction.  an et+18 on a 9.5" wheel width does roughly equate to a 6" backspace. (5.9xx) 

 

The math to find backspacing from rim width and offset is as follows:

Step 1.  Add 1" to the rim width to account for the wheel flanges.

Step 2. Divide by 2 to find wheel centerline.

Step 3: Convert the offset to inches. Add to centerline measurement if offset is positive, subtract if negative.

 

Thus. 9.5 width +1" = 10.5"

10.5/2 = 5.25"

18mm / 25.4 = .708"

5.25+.708 = 5.958" backspace

 

Hopefully that clears it up a bit.

 

 

 

 

 

Thanks, that did.

[Jeep Driver]

 

 

Wheel Technical Information

• Brand- American Racing Vintage
• Model- Blvd
• Finish- Satin Black Machined
• Wheel Diameter- 18
• Wheel Width- 9.5
• Wheel Offset- 0
• Wheel Backspace- 5.25
• Wheel Bolt Pattern- 5 x 114.3/4.5
• Wheel Hub Bore- 72.6
• Center Cap Included?- Yes

 

 

 

 

 

Does anyone see a problem with this wheel and a 3" lift? Considering the tire will be at 31.4"?

[Jeep Driver]

We have made a decision-