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17x9 wheels bs 17x8.5 jkur

489 Views 4 Replies 2 Participants Last post by  Todml
With 285 70 17 tires have seen posts recommend 17x9 wheels with 4.75 backspacing to maintain slightly positive scrub ratio. Will 17x8.5 wheels with 4.75 backspacing adversely affect scrub ratio turning it neutral or negative? Thanks in advance
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your CS was correct when it was on stock wheels and tires with what was it 6.5 BS. So that is your target. Tire diameter and the BS all effect that target of being in CR range. going say moved that point a lot. The tire will be more a 32 on the jeep, that is stock on a Rubicon anyway. But stock rubi 32s were more like 31.5 as well. So you have a real 32. not much changed but that BS of 4.75. You try those on stock wheels? would give best CR for you and the thinner wheel hold better at air down by a lot. I would run a 8.5 on any 12.5 wide tire as long as enough side wall. I run a 17x9 at 4.25 on a 37. still rubs a bit at lock in stuff.

ratio wise you off even with .5 narrower on the out side of center point is hitting inside edge. Most jeepers really dont care about CR. It does effect how tire handles on street mosty.

standard BS fro say 35x12.5x XX 4.5" 37" its more 4-4.25< rubs a bit at lock. 40s will need 3.5.. Taller tire makes up for CR to a point. I had 35 on a 15" wheel on a jk and to make that work you must have no more then 3.75bs 3.5 would have been better. THe CR was total wack. drove about 4 years that way. then went to 37s at 4.25. Thing went from feeling looser then i like and not cornering well ( jeep is not a sports car). it takes handle a lot better on 37 street that do not run much anyway. but that jeep can cut corners rather good for 4.5 lift as well. But i moved track bar roll centers. steering as well. front and rear. less wagging.
 

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Discussion Starter · #3 ·
Layed it out on workbench after post and from 10.04 w/32.06dia to11.20w/32.80dia came up with about +1.78 minus a little for .78 larger diameter,1/4? hard to get right without knowing suspension axis inclination? so1 1/2 more positive on the 17x8.5(a little less positive than the 17x9) Does this sound like I am figuring it right? Thanks
 

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2017 Jeep JKUR
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12 Posts
Discussion Starter · #4 ·
Layed it out on workbench after post and from 10.04 w/32.06dia to11.20w/32.80dia came up with about +1.78 minus a little for .78 larger diameter,1/4? hard to get right without knowing suspension axis inclination? so1 1/2 more positive on the 17x8.5(a little less positive than the 17x9) Does this sound like I am figuring it right? Thanks
Also looks about 1 1/2 more clearance inside is that enough so I would have no interference? Would I need to put maybe a 1/2 inch spring spacer? Thanks again
 
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