zagscrawler Posted June 20, 2011 Share Posted June 20, 2011 Does anyone know the proper backspacing i need to run to clear 35x12.5 KM2 on a 15" rim. The front should be lifted around 6.5 inches when all is said and done. Its a hp dana 30. Thanks in advance. Link to comment Share on other sites More sharing options...
philbert001 Posted June 20, 2011 Share Posted June 20, 2011 3 inches on a 15x10 rim should do it for ya. I'm running 4 inch backspaced 16x 8's and clear 285's, (33.4x12.5) with about 1/2 inch to the control arm. If you still rub a little, throw a couple washers in behind your steering stops. If you go with anything wider than 3 inches, you'll be putting a LOT more stress on all your front end/steering components. Link to comment Share on other sites More sharing options...
philbert001 Posted June 20, 2011 Share Posted June 20, 2011 And as of now, I have about 6 inches of lift up front on short arms. Link to comment Share on other sites More sharing options...
zagscrawler Posted June 21, 2011 Author Share Posted June 21, 2011 I do plan on running a long arm set up (clayton is my fave so far) when i put all the lift and 4x4 parts on this bad boy, is that going to make a difference with rubbing the lowers? I keep hearing around 4-4.5 inches is real common backspacing, am i mistaken? Also if some one can post a pic or two of the 35's with a similar backspacing i would like to see what i am going to look like :D thanks all Link to comment Share on other sites More sharing options...
philbert001 Posted June 21, 2011 Share Posted June 21, 2011 I believe stockers are 5 or 5.5. I run 4, but most guys I know run 3. With 35s, I think you would run into rubbing/turning issues with anything narrower than 3. Link to comment Share on other sites More sharing options...
zagscrawler Posted June 22, 2011 Author Share Posted June 22, 2011 I don't mean to bug but how come i shouldn't run 8 inch wide wheels? Cause of the 15 inch dia. on the wheels? If i can run a 8 inch wide wheel what should the back spacing look like? I got schooled on how to measure backspacing from one of my tire buds and i think i can find a similar backspacing on a 8 inch wheel. Any ideas? Thanks Zag Link to comment Share on other sites More sharing options...
philbert001 Posted June 22, 2011 Share Posted June 22, 2011 I only suggested 10 wide because you are running 35s. If you were running 33's, I'd run 8 wide, but on 35s, you'd be pulling the tire in an awful lot. If you can get a deal on 8 wide, you'd probably be ok, since you aren't running super wide 35s, but if ordering new, I'd spend the extra $ and go for ten wide. Either way, the backspace will measure the same, and I would run 3 inch either way. Link to comment Share on other sites More sharing options...
zagscrawler Posted June 22, 2011 Author Share Posted June 22, 2011 I see what you mean as far as 10 wide. As far as backspacing i heard today that the measurement starts with the width of the wheel and was divided. He even went to say you measure from the outside width ( 9" on a 8" wheel) of a wheel to start the backspacing measure? He might of been crazy but i don't know for sure :dunno: Link to comment Share on other sites More sharing options...
philbert001 Posted June 22, 2011 Share Posted June 22, 2011 Backspacing is the measurement from the inside lip of the rim, to the hub. Hence, 3 inch backspaced rims, means that the hub of the wheel is 3 inches in from the back edge of the rim. Best way to measure, (easier Without tires), Run a straight edge across the backside of the wheel, and measure from the straight edge, to the inside of the hub. The measurement your buddy was talking about is the offset. (How far off center the hub is in the wheel) Link to comment Share on other sites More sharing options...
Motion Offroad Posted June 22, 2011 Share Posted June 22, 2011 We've ran 35's on a 8" rim for years without issues (even airing down to 12psi without beadlocks). I personally wouldn't run a 10" wide rim as you pop the bead a lot easier. With a 8" wide rim you'll want 3.5-4" backspacing with a 12.5" wide tire. Here is a photo for reference running 35x12.5 with a 15x8 w/3.75" BS. Link to comment Share on other sites More sharing options...
philbert001 Posted June 22, 2011 Share Posted June 22, 2011 I am running 33s with 4 inch backspaced wheels, and at full flex, she rubs framerails out back. (SOA 35, healthy stock springs, about 5.5 inches on top of an already healthy rear stance.) There's one more reason to go with less backspace. Link to comment Share on other sites More sharing options...
zagscrawler Posted June 22, 2011 Author Share Posted June 22, 2011 Thanks a bunch for all the info. I really dig the way that truck looks in that pic :thumbsup: How much lift is that ? Again thanks guys for all the help and i think i know what to do now. :banana: Link to comment Share on other sites More sharing options...
kawaboy13 Posted June 22, 2011 Share Posted June 22, 2011 What bumper is that on that blue MJ? That looks clean Link to comment Share on other sites More sharing options...
Boots Posted June 22, 2011 Share Posted June 22, 2011 :agree: It looks green to me. Link to comment Share on other sites More sharing options...
Eagle Posted June 22, 2011 Share Posted June 22, 2011 I see what you mean as far as 10 wide. As far as backspacing i heard today that the measurement starts with the width of the wheel and was divided. He even went to say you measure from the outside width ( 9" on a 8" wheel) of a wheel to start the backspacing measure? He might of been crazy but i don't know for sure :dunno: Backspacing is not the same as offset. Backspacing is the dimension from the wheel mounting surface to the inner flange of the rim. Stock for an XJ or MJ with 15x7 OEM rims is 5-1/4". Backspacing does not take into account rim width or centerline. If you have a 15x10 rim and a 15x8 rim, and they both have 4" of backspacing, the 15x10 rim will extend OUT by 2 more inches. They will both be the same distance from the control arms. That's for the rim. If the inner flange is in the same position for both but the 15x10 has the outer flange 2" farther outboard, then obviously the centerline of the 15x10 must be 1" farther outboard than a 15x8. So now if you mount a 12.5" tire on each rim, the centerline of the tire will be 1" farther out with the 15x10 ... or the centerline of the tire will be 1" closer to the control arms with the 15x8, even though the inboard flange is in the same position. Link to comment Share on other sites More sharing options...
Motion Offroad Posted June 22, 2011 Share Posted June 22, 2011 Lift is a Motion Offroad 6.5" Bumper is a Warrior Products Rock Crawler w/Custom 4x4 Fabrication Tow Hooks Link to comment Share on other sites More sharing options...
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