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Discussion Starter · #1 ·
I have a 2020 2-door Sport S, totally stock.

I bought a set of 285/70/17 BFG KO2s. I’ve decided on Black Rhino Warlord rims.

They come in two sizes: 17x8 +30mm (5.7” backspacing) or 17x9 -12mm (4.5” backspacing).

My understanding of pros and cons:

17x8: Pros - fit under fenders (potentially a requirement where I live - unclear), should theoretically fit. Cons - may rub at full lock or offroad

17x9: Pros - should definitely fit without rubbing. Cons - will sit outside fenders which may be illegal where I live. Wider stance may cause additional wear & tear on joints, parts, etc.

Which do I pick?? I already bought the 17x8 but now having concerns. I have a few days left where I could still switch before they ship. Just would hate to spend all this money on wheels and then need spacers.

Not looking to lift it right now, but open to potentially throwing on takeoff rubicon suspension down the road. For now, just looking for a wheel that’ll fit on stock suspension without rub.

Thanks in advance friends
 

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This is far from a definitive answer, but here’s what I found with a little research.

To start, a stock Rubicon comes with the tire size you bought on 7.5” wide wheels with 6.1” of backspace; however, the Rubicon axle is 1.5” wider than a sport. Doing the math, that yields 8.1” from the hub face to the inside of the tire.

Your 8” wide wheels with 5.7” of backspace should yield 7.45” from the hub face to the inside of the tire. Add .75” for the narrower sport axle and you get 8.2”, so that setup should place the inside of your tires 0.10” closer to the frame and suspension than a stock Rubicon. Would this rub? Probably not, but I can’t say for sure.

I personally would go with the 9” wide wheel with 4.5” backspace. You definitely won’t have a rub and I like the looks of the tire fully filling the width of the flares. These wheels will put the tires 0.7” outboard of where the tires would sit with the 8” wide Black Rhino wheels.

Hope this info helps you make a decision.


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Discussion Starter · #3 ·
This is far from a definitive answer, but here’s what I found with a little research.

To start, a stock Rubicon comes with the tire size you bought on 7.5” wide wheels with 6.1” of backspace; however, the Rubicon axle is 1.5” wider than a sport. Doing the math, that yields 8.1” from the hub face to the inside of the tire.

Your 8” wide wheels with 5.7” of backspace should yield 7.45” from the hub face to the inside of the tire. Add .75” for the narrower sport axle and you get 8.2”, so that setup should place the inside of your tires 0.10” closer to the frame and suspension than a stock Rubicon. Would this rub? Probably not, but I can’t say for sure.

I personally would go with the 9” wide wheel with 4.5” backspace. You definitely won’t have a rub and I like the looks of the tire fully filling the width of the flares. These wheels will put the tires 0.7” outboard of where the tires would sit with the 8” wide Black Rhino wheels.

Hope this info helps you make a decision.


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Definitely helpful, I really appreciate it. I am learning all these calculations. How do you calculate the distance from hub face to inner tire of 8.1 and 8.2”, respectively?

When you say the 17x9s would sit .7” further outbound than the 17x8s, what do you mean? When I punch these figures into various calculators, it tells me that the 17x9 (compared to the 17x8) would yield 29mm more inner clearance and push the outer position of the wheel 55mm further away from the body of the car.

The 4.5” backspacing makes me comfortable that it wouldn’t rub, but results in the tire being visibly outside the fenders, which is potentially illegal in Washington DC (laws aren’t clear). Also, I read something somewhere that a wider stance puts additional stress on various parts (is that true - particularly for a stock JL sport s)? Also, if the tires are outside the fenders, isn’t there some risk that the tires will kick up rocks against my new paint while driving?

Last question (I know this is a lot) - what do you mean “I like the looks of the tire fully filling the width of the flares” - do you just mean you like some poke out past the fenders? When I compare my stock setup to the 285/70/17 w/ 17x9 and 4.5” backspacing, it says that it will poke out almost 3” past fender flares, so that brings me back to this whole legality / wear & tear / throwing rocks against paint point.

Maybe I should try to call DMV to confirm laws. Sigh…

Thank you so much for the response!
 

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To calculate hub face to inside of tire, take the section width of the tire (11.5”), minus the width of the wheel (8”) and divide by 2. This gives you the amount that the tire side wall will protrude past the edge of the wheel, in this case 1.75”. Backspace is the measurement from the wheel mounting surface to the inside edge of the wheel (5.7”). Add the tire protrusion to the backspace to get hub face to inside of tire. In this case, 7.45”. To get the 8.2”, I added 0.75” because I was comparing it to measurements for a Rubicon, which has a 1.5” wider axle than the sport (.75” per side). If you were to measure on your Jeep, tire should actually be 7.45” hub face to inside of tire with the 8” wide Black Rhinos.

I’ve got 9” wheels with 1mm offset on my Rubicon with 12.5” wide tires. My axle is .75” wider (per side) than yours and my tire would protrude .5” more past the wheel than yours. So that’s a total of 1.25” that my tires should stick out more than yours, but the 9” Black Rhino wheels have an offset of -12mm, so that’s 13mm (0.51”) more backspace than my wheels. Take that from the 1.25” and my tires should still stick out 0.75” more than yours. I never measured exactly, but my tires are less than 3” past the edge of my fenders.

I live in MD and we are not allowed to have the tires protrude past the fenders. This can be a big deal for inspection, but that only happens when the vehicle is purchased used. You can be given an equipment repair order by the police at any time, but unless they stick way out, that very rarely happens. If DC doesn’t require yearly inspections, it probably won’t be an issue for you.


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Discussion Starter · #5 ·
To calculate hub face to inside of tire, take the section width of the tire (11.5”), minus the width of the wheel (8”) and divide by 2. This gives you the amount that the tire side wall will protrude past the edge of the wheel, in this case 1.75”. Backspace is the measurement from the wheel mounting surface to the inside edge of the wheel (5.7”). Add the tire protrusion to the backspace to get hub face to inside of tire. In this case, 7.45”. To get the 8.2”, I added 0.75” because I was comparing it to measurements for a Rubicon, which has a 1.5” wider axle than the sport (.75” per side). If you were to measure on your Jeep, tire should actually be 7.45” hub face to inside of tire with the 8” wide Black Rhinos.

I’ve got 9” wheels with 1mm offset on my Rubicon with 12.5” wide tires. My axle is .75” wider (per side) than yours and my tire would protrude .5” more past the wheel than yours. So that’s a total of 1.25” that my tires should stick out more than yours, but the 9” Black Rhino wheels have an offset of -12mm, so that’s 13mm (0.51”) more backspace than my wheels. Take that from the 1.25” and my tires should still stick out 0.75” more than yours. I never measured exactly, but my tires are less than 3” past the edge of my fenders.

I live in MD and we are not allowed to have the tires protrude past the fenders. This can be a big deal for inspection, but that only happens when the vehicle is purchased used. You can be given an equipment repair order by the police at any time, but unless they stick way out, that very rarely happens. If DC doesn’t require yearly inspections, it probably won’t be an issue for you.


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This is great, really appreciate it. I actually went up and ran Frederick Watershed a couple weeks ago. Not sure I would call it an off-road trail, but nice scenery and only about an hour from me. Are there any other good spots in MD?

Thanks for the calculations. Is it true that 4.5” would put additional stress on joints, etc. and lead to additional wear & tear?

And as far as DMV, I bought new so I don’t need an inspection until 2024. But I don’t totally understand the law, so I went with 5.7” backspace to be safe.

How do you interpret this?

“No motor vehicle shall be operated on the streets and highways if fenders, running boards, bumper bars, or any body part shall extend beyond the original margin or width of the fender lines, except as provided in § 733.7.”

note: 733.7 applies to work trucks carrying ladders and equipment
 

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MD is pretty tough for off-roading. They closed all of the trails several years ago. They did open an “off-road” area in the western part of the state, but I have not been there. Seems more geared to ATV’s and dirt bikes.

The law you quoted seems to apply to body and accessories, but it could be interpreted to include tires. I would check with some of your local Jeepers to see if they have had any issues.

As far as wear, it does put more stress on components such as ball joints, but I ran 35” tires on 9” wide wheels with 4.50” backspacing on my 13 JKU for 80K miles and never had to replace anything.


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This is great, really appreciate it. I actually went up and ran Frederick Watershed a couple weeks ago. Not sure I would call it an off-road trail, but nice scenery and only about an hour from me. Are there any other good spots in MD?

Thanks for the calculations. Is it true that 4.5” would put additional stress on joints, etc. and lead to additional wear & tear?

And as far as DMV, I bought new so I don’t need an inspection until 2024. But I don’t totally understand the law, so I went with 5.7” backspace to be safe.

How do you interpret this?

“No motor vehicle shall be operated on the streets and highways if fenders, running boards, bumper bars, or any body part shall extend beyond the original margin or width of the fender lines, except as provided in § 733.7.”

note: 733.7 applies to work trucks carrying ladders and equipment
I don't know if I would call them "good spots", but there are some trails west of Frederick out in the Greenridge State Forest, out by Orleans off I-68. They are basically forest roads through the forest, some are dirt and some are 4x4 only.
There is also a good area when they have events down in WV by Capon Bridge. But they are only when they are having an event, the place is called Chaos Offroad Park.
Then there are two excellent locations up in PA off I-81, Rousch Creek and Anthracite Outdoor Adventure Area (AOAA).
Maryland doesn't seem to be an issue with tires sticking out past fenders, at least we have never had an issue or know someone who has had in issue in Maryland.
I would go with the 4.5" backspacing wheels, personally. I think 5.2" of backspacing is good, but 5.7" backspacing will probably rub.
 

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What state do you live in? I live in california and never had any issues with my tires poking out around 2 inches past the fender
 

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The law you quoted above applies to body parts, and not tires. There MAY be something about tires there, but what you quoted is NOT the reference.
 

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Discussion Starter · #11 ·
The law you quoted above applies to body parts, and not tires. There MAY be something about tires there, but what you quoted is NOT the reference.
Ok cool. I read the entire statute and this was the closest thing I saw to a fender law.
 

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As far as wear, it does put more stress on components such as ball joints, but I ran 35” tires on 9” wide wheels with 4.50” backspacing on my 13 JKU for 80K miles and never had to replace anything.


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Anything that puts the wheels further out, or increases their mass, is going to cause 'more stress'. Is it still within spec for that axle? In your case, yes it is. Going to a 285 tire (33) with another inch of spacing is not going to exponentially overload the axle. Remember, you can get 315's (35s) right from the factory now.

As for kicking up rocks - you bet. If you don't have some kind of running boards or mud flaps you will absolutely chew the crap out of the leading edge of your door hinges, and the rear fenders - if you drive on roads with lots of debris. Where I live, winter road sanding KILLS paint on all kinds of vehicles.
 

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I am not sure this helps much but here in Utah we have a tire law as well. On my 2020 JLUR I put 35s and larger wheels that put the tires out about 1.2" past the fender flares. I ran with that for about a year before I sold the Jeep but had no issues. What you will have is the inspection issue. You might get an inspector that is not picky or you can get one that is nutso. I don't really think they will notice .7" outside the flares. I also put larger wheels and tires on my 2014 JLUR that is still in the family and it has never been an issue even with our tire law here. I think that one is at least 1" outside the flares.
 

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First: 35" is the proper size😃

And then more seriously: 285 is right at the top of the wheel width range with 9" wide wheels, which is not optimal for offroading. The wider the wheel, the more likely you are to pop the tire off the bead.

I run 315/70 R17 on 9" wheels, and it looks and feels right, if that is of any significance.

I personally would keep backspacing as big as possible as long as tires wont rub. This will keep axle strain to minimum.
 

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DC. Law quoted above.
I recommend asking people in your area who have jeeps or trucks with tires sticking out if they have ever been pulled over for it. I believe california has a tire poking out law as well, but we have literally 10 inch lifted monster trucks with none of the tire being covered on the road constantly. I’ve never been pulled over for 2 inches of tire sticking out.
 

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Discussion Starter · #17 ·
First: 35" is the proper size😃

And then more seriously: 285 is right at the top of the wheel width range with 9" wide wheels, which is not optimal for offroading. The wider the wheel, the more likely you are to pop the tire off the bead.

I run 315/70 R17 on 9" wheels, and it looks and feels right, if that is of any significance.

I personally would keep backspacing as big as possible as long as tires wont rub. This will keep axle strain to minimum.
Baby steps...baby steps...I hear you. Honestly, I wish they made this wheel in 5.22 or 4.75 backspacing, I think that would be ideal. Unfortunately, it's either 17x8 at 5.7" or 17x9 at 4.5".

The question is whether 5.7" is enough or if I am going to rub. I would say I'll do 95% city / highway driving. Then probably try to do 5-10 mild off-roading trips to local trails per year. If I lived in a more off-road plentiful place, it'd be more, but this is DC.

That said, what do you think? I'll be removing the euro flaps...more concerned about rubbing on sway bar or other inner parts when making tight turns.
 

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Unfortunately mine is a JKU, so can't really say. I've checked out a Rubi JLU nearby last summer, it had 315/70R17's on stock wheels, and it was nowhere near rubbing at full lock. So I'd refer back to the math by dwtgolden (iirc).

I know this wheel/tire stuff can be nerve wrecking, when I was gettin new wheels, the most common comment was 4.5" bs for 35's is the minimum (for JK). I did my own math, and it turns out 4.5" was bullshit. I have 5" bs, and no problems at all, prolly could gave gone 5.5 but didn't find any wheels so didn't have to worry about that.

Are spacers legal where you ride? You can always push the wheel outwards with those, but not the other way around....
 

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Discussion Starter · #19 ·
Unfortunately mine is a JKU, so can't really say. I've checked out a Rubi JLU nearby last summer, it had 315/70R17's on stock wheels, and it was nowhere near rubbing at full lock. So I'd refer back to the math by dwtgolden (iirc).

I know this wheel/tire stuff can be nerve wrecking, when I was gettin new wheels, the most common comment was 4.5" bs for 35's is the minimum (for JK). I did my own math, and it turns out 4.5" was bullshit. I have 5" bs, and no problems at all, prolly could gave gone 5.5 but didn't find any wheels so didn't have to worry about that.

Are spacers legal where you ride? You can always push the wheel outwards with those, but not the other way around....
I hear you. DC does not have explicit laws that govern wheels (incl. spacers). It would just break my heart to spend $250 a pop on beautiful wheels and then need to buy spacers. I am in love with the Black Rhino Warlords, but they only come in 4.5 or 5.7....I honestly think the 5.7 will work, but of course I am overthinking...
 

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With the JK generally between 4.5” and 5.2” is the sweet spot for backspacing.
For the non-Rubicon JL I suspect it is the same.
 
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