Confirming things about wheel backspacing
I'm working on a stage 1 build for my 2010 JK. I've got the 16x7 stock steelies, and I've put some ~32" tires on them to fill up some of that ugly gap in the wheel well.
One thing that always bothered me about the JK is how on the 2010 model the tires aren't flush with the side flares. I'd prefer them either flush or sticking out a bit so the rig doesn't look like it has flare-hips.
I've read a bit on backspacing, but I want to make sure that I'm right about the wheels. I'm going to stick with 16" rims until my next stage build, and I've got my eyes set on the Pro Comp Alloy Series 5029.
New wheels: 16x8; 5in backspace
Stock steelies: 16x7; 6.25in backspace
I've worked up an image of how I think this will play out. Is this all right?

I'm thinking these new wheels will push out the tires about 2", putting them about flush with the sides. Can anyone confirm that, or recommend a comparable wheel that will get me flush or a little further out than the flares?
I also found a photo on JK-forum of a gorgeous JK with 35"x12.5" tires, which brought me to thinking: I can't figure out the difference between the wheel width and the tire width. Will any 16" tire fit on a 16" rim?
One thing that always bothered me about the JK is how on the 2010 model the tires aren't flush with the side flares. I'd prefer them either flush or sticking out a bit so the rig doesn't look like it has flare-hips.
I've read a bit on backspacing, but I want to make sure that I'm right about the wheels. I'm going to stick with 16" rims until my next stage build, and I've got my eyes set on the Pro Comp Alloy Series 5029.
New wheels: 16x8; 5in backspace
Stock steelies: 16x7; 6.25in backspace
I've worked up an image of how I think this will play out. Is this all right?
I'm thinking these new wheels will push out the tires about 2", putting them about flush with the sides. Can anyone confirm that, or recommend a comparable wheel that will get me flush or a little further out than the flares?
I also found a photo on JK-forum of a gorgeous JK with 35"x12.5" tires, which brought me to thinking: I can't figure out the difference between the wheel width and the tire width. Will any 16" tire fit on a 16" rim?
Google Image Result for http://www.readylift.com/Images/tech-wheeloffset.gif
You generally need 4.5" of backspace to or less to avoid tire rub issues. If your looking at rims that use offset check out the link. And yes a 16" tire will only fit a 16" rim (16" is the diameter).
You generally need 4.5" of backspace to or less to avoid tire rub issues. If your looking at rims that use offset check out the link. And yes a 16" tire will only fit a 16" rim (16" is the diameter).
Last edited by hooper; Dec 10, 2013 at 07:37 PM.
Stock 17" wheels with spidertrax spacers sit flush with the flares. There are a ton of people running this combo to confirm that but the numbers that are important there (for you) would be the wheel width, backspacing, and effective backspacing after the spacer.
If you're really just looking to achieve the perception that your tires don't sit in so far then I would recommend also chopping the bumpers as they only accentuate the wide flares.
With the tires sticking out ~2" or so from where you are now you'll be set. If you goof up and put them 2" outside of the fender then you won't be a happy camper. Driving anywhere instantly gets both sides of the vehicle instantly dirty- been there, done that, got the tshirt and pics.
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If you're really just looking to achieve the perception that your tires don't sit in so far then I would recommend also chopping the bumpers as they only accentuate the wide flares.
With the tires sticking out ~2" or so from where you are now you'll be set. If you goof up and put them 2" outside of the fender then you won't be a happy camper. Driving anywhere instantly gets both sides of the vehicle instantly dirty- been there, done that, got the tshirt and pics.
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Just to clarify — I'm not looking at spacers. I'm looking at a new set of wheels and I want to make sure that my math/understanding of backspacing is correct and they will stick out about 2 inches more than my current stock steelies. And what do tires have to do with the wheels?
Hooper: stock steelies have a backspacing of 6.25" —*I know that 4.5" is the magic number here, but my 6.25" backspaced steelies don't rub so I don't think 5" of backspace will rub either. Am I right?
Hooper: stock steelies have a backspacing of 6.25" —*I know that 4.5" is the magic number here, but my 6.25" backspaced steelies don't rub so I don't think 5" of backspace will rub either. Am I right?
Just to clarify — I'm not looking at spacers. I'm looking at a new set of wheels and I want to make sure that my math/understanding of backspacing is correct and they will stick out about 2 inches more than my current stock steelies. And what do tires have to do with the wheels?
Hooper: stock steelies have a backspacing of 6.25" —*I know that 4.5" is the magic number here, but my 6.25" backspaced steelies don't rub so I don't think 5" of backspace will rub either. Am I right?
Hooper: stock steelies have a backspacing of 6.25" —*I know that 4.5" is the magic number here, but my 6.25" backspaced steelies don't rub so I don't think 5" of backspace will rub either. Am I right?

Yes, you will be less likely to rub holding tire size constant. Make sure to consider the section width of the tire since most are wider than 8". So, your tire will stick out further than the rim.
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This is how I calculate it which makes the math easier.
8" rims with 5" of backspacing leaves 3" of front spacing.
7" rims with 6.25 backspacing is .75" front spacing.
So yes you will be pushing your front rim edge out 2.25". Another part of the equation is the width of the tire in regards to how much it will overhang the edge of the rim.
8" rims with 5" of backspacing leaves 3" of front spacing.
7" rims with 6.25 backspacing is .75" front spacing.
So yes you will be pushing your front rim edge out 2.25". Another part of the equation is the width of the tire in regards to how much it will overhang the edge of the rim.


