Spacer/Adapter sizing question

[hear]

I picked up some JK wheels & tires, so now I need adapters to correct the bolt pattern. Figuring out what size spacer is probably more confusing to me than it should be, but here goes.

I guess question 1 is what is the minimum thickness spacer to clear the existing studs?

And then question 2 is how thick do I need them to be to give me the right backspacing & all that?

The tires are 17"x7.5", and the offset is 44.45mm. I'm assuming its in mm, although why we measure some things in Freedom Units and others in metric I'll probably never understand. My existing wheels are pro-comp 15"x8" steel wheels, which look to have a -19mm offset, but I don't know that for a fact.

 

[Tronner]

When I had JL rims on my TJ, I used 2inch spacers to gain factory TJ Rubicon back spacing.

 

[jjvw]

I picked up some JK wheels & tires, so now I need adapters to correct the bolt pattern. Figuring out what size spacer is probably more confusing to me than it should be, but here goes.

I guess question 1 is what is the minimum thickness spacer to clear the existing studs?

And then question 2 is how thick do I need them to be to give me the right backspacing & all that?

The tires are 17"x7.5", and the offset is 44.45mm. I'm assuming its in mm, although why we measure some things in Freedom Units and others in metric I'll probably never understand. My existing wheels are pro-comp 15"x8" steel wheels, which look to have a -19mm offset, but I don't know that for a fact.

Ignore offset. JK wheels have 6" backspacing. Whatever thickness adapter spacer you use will deduct from that 6" to create the effective backspacing.

Mine have an effective backspacing of 4".

 

[hear]

Sonia that to say I need 2” spacers since 6” - 4” = 2”?

 

[CharlesHS]

When I installed the JK rims I used G2 (94-6573-125) 1.25" adapter spacers which are hub centric.

https://www.ebay.com/itm/1468525184...pid=5337789113&customid=&toolid=10001&mkevt=1

 

[TheBoogieman]

Sonia that to say I need 2” spacers

Sonia is a feminine given name in many areas of the world including the West, Russia, Iran, and South Asia.

 

[TheBoogieman]

And then question 2 is how thick do I need them to be to give me the right backspacing & all that?

Depends on tire width.

The tires are 17"x7.5"

 

[jjvw]

Sonia that to say I need 2” spacers since 6” - 4” = 2”?

That is something she would say.

 

[JMT]

Sonia that to say I need 2” spacers since 6” - 4” = 2”?

Current backspacing is 6”.
Add a spacer that is 2” reduces your backspace 2”.
6-2=4” overall backspace.

 

[mrblaine]

I picked up some JK wheels & tires, so now I need adapters to correct the bolt pattern. Figuring out what size spacer is probably more confusing to me than it should be, but here goes.

I guess question 1 is what is the minimum thickness spacer to clear the existing studs?

Not quite as cut and dried as that. Some wheels have indented area between each wheel stud hole that a small bit of the existing wheel stud can poke into when the wheel is mounted to the spacer/adapter. That ignores the fact that wheel studs can be trimmed if needed provided you have full lug nut thread engagement.

That said, the narrowest adapter I see is generally 1".

And then question 2 is how thick do I need them to be to give me the right backspacing & all that?

The tires are 17"x7.5", and the offset is 44.45mm. I'm assuming its in mm, although why we measure some things in Freedom Units and others in metric I'll probably never understand. My existing wheels are pro-comp 15"x8" steel wheels, which look to have a -19mm offset, but I don't know that for a fact.

If you are happy with your current steering and handling and wish to mimic or maintain that, measure your current backspacing. That is done by laying the outer face down and a straight edge across the wheel close enough to the center that you can measure down to the face of the wheel mounting surface.

Once you have that number, then you can use it to copy the same to the new wheels with some basic math, or improve it if desired. The biggest mistake I see on here due to lack of any understanding about the benefits of good backspacing is moving the wheels out too far to "improve stability". While that may make it slightly better for resistance to tipping over, the crappy steering you get in return is not a good compromise if you care about such things.
I will apologize in advance for the pictures after the correct one since they illustrate my pet peeve about folks who simply lack basic common sense about straight edges and how they work.
This is correct, the straight edge can't bow and alter the measurement.

This and a few others were done by idiots.