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Discussion Starter · #1 ·
I can't decide if I should run 4.5, 4, or 3.75 backspacing. My lift was designed for 17x9 with 4.5 backspacing, but I plan to run 17x8's with 37x12.5 tires on my JK unlimited.

Can anyone please post pics of how far their tires stick out past the fenders with their backspacing?

Thanks very much.
 

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Discussion Starter · #3 ·
From the manufacturer: "This suspension system was designed around a 17x9 wheel with a 4½” back spacing. Other wheel & tire configurations can be used but interference may be an issue."

Think that simply means you can use this wheel config and not have problems with wheel/tire clearance - makes sense.

Still, simply want to see pics of what others have been running and their preferences.

Looking forward to any pics. Thanks.
 

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i dont have a lift, but im running 17x9 with 5" backspacing



they stick out about a half inch from the fenders.
 

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8.5" wide wheels with 4.5" of backspacing... running 33x11.50 tires. About 1" outside the flares.
 

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17x9.5 with 3.5 BS


2-3" outside fender!


Have noticed a huge difference in stability!
steve, is it better stability?
sorry im new to jeeps lol
once i get my lift i'll probably need spacers, which will put me to about 4, or 3.5 backspacing
 

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....Think that simply means you can use this wheel config and not have problems with wheel/tire clearance - makes sense.
....
Makes only some sense for clearance issues with the wheel but not for the tire since it does not mention the associated tire width/diameter which has a huge impact on clearance ;)


315/75R16 (~35X12.5") on 16X8 - 4.5"BS (0 Offset) wheels which is just a little too tight and rubs at steering lock. Just stick a little bit past the flatties.

With 37X12.5 on 9" wide wheels I would say you'll need 3.75 - 4" Backspacing
 

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From the manufacturer: "This suspension system was designed around a 17x9 wheel with a 4½” back spacing. Other wheel & tire configurations can be used but interference may be an issue."
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Most lift manufactures that add info like this are stating thats what they bolted to their vehicle during the design of their kit. Assuming the wheel you choose will clear the vehicles brakes a narrower wheel with the same or lower backspace should clear any new suspension parts that may be added with this kit (wheel only, not necessarily with any tire). This usually makes no assumptions for your tire choice and you may need to go with a wheel with a lower offset/backspace to clear the tire you want to run.

17x8's are a little narrow for a 37x12.50R17 tire. Most tire manufacturer's recommend an 8.5" wide wheel at minimum.

For reference here's some wheel specs that have 4.5" Backspacing and would be approved for a 37x12.50R17 tire.

17x8.5 -6mm offset
17x9 -12mm offset
17x10 -25mm offset


With all this said, What are you trying to do? What lift are you installing and how do you want your wheels and tires to sit?
 

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Discussion Starter · #10 ·
Most lift manufactures that add info like this are stating thats what they bolted to their vehicle during the design of their kit. Assuming the wheel you choose will clear the vehicles brakes a narrower wheel with the same or lower backspace should clear any new suspension parts that may be added with this kit (wheel only, not necessarily with any tire). This usually makes no assumptions for your tire choice and you may need to go with a wheel with a lower offset/backspace to clear the tire you want to run.

17x8's are a little narrow for a 37x12.50R17 tire. Most tire manufacturer's recommend an 8.5" wide wheel at minimum.

For reference here's some wheel specs that have 4.5" Backspacing and would be approved for a 37x12.50R17 tire.

17x8.5 -6mm offset
17x9 -12mm offset
17x10 -25mm offset


With all this said, What are you trying to do? What lift are you installing and how do you want your wheels and tires to sit?
Thanks for the great info. Lift will be 4" short arm. I wanted to run a 8" wide tire because I'm told that holds the bead better when aired down (don't want to run bead locks at this point). I assume 8.5" - 9" will not make that big a difference as far as holding a bead better when aired down?

I also want stability and think it looks better when the tire sticks out past the fender a little bit (up to a couple/few inches but not much farther). Fenders will be stock for now but eventually will upgrade to flat fenders.

Thanks again.
 

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Thanks for the great info. Lift will be 4" short arm. I wanted to run a 8" wide tire because I'm told that holds the bead better when aired down (don't want to run bead locks at this point). I assume 8.5" - 9" will not make that big a difference as far as holding a bead better when aired down?

I also want stability and think it looks better when the tire sticks out past the fender a little bit (up to a couple/few inches but not much farther). Fenders will be stock for now but eventually will upgrade to flat fenders.

Thanks again.
I've run 9psi on 17x9" wheels with 37" tires and haven't lost a bead (yet) With the amount of bulge I got at 9psi I haven't wanted/needed to go any lower. I find 11psi seems to work best for me on most trails and at 11psi its possible but it will take some good effort to blow the bead. I've run some serious trails and during JKX for the last year as well as trails in Moab during easter jeep safari and haven't had any issues with it this far.

An 8" wide wheel with a 4.5" backspace will sit pretty flush. If you want them to stick out past the fenders you'll want a wider wheel.

Here's a 17x8.5 with a 4.5" backspace and 35x12.50R17 tires (stock fenders 4" Rock Krawler mid arm lift):


Here's a 18x9" with a 4.5" backspace 37x13.50R18 tires. (flat fenders, 6" Teraflex long arm)


Here's an 8" wide wheel with a 3.75" Backspace and 35x12.50R15 tire. (An 8" wide wheel with a 4.5" backspace will be tucked under the jeep .75" more.)
 
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