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Unread 12-08-2013, 09:34 AM   #1
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Power/performance question

Anyone with a JKUR running 5:13 gears, a RIPP supercharger, and 37 in tires? My JKUR has this set up currently with an automatic and 35 in tires and set up is great. The reason I ask question is because I am thinking about going up to 37 in tires when my 35's wear out. I am wondering what power will be like. I will be only adding 8-12 lbs total by going from 35in mt Mtz's to 37 in mtr kevlars or km2's. I am getting ready to put on high altitude pulley which the added power should make set up with 37's feel like set up with 35's some input would help.

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Unread 12-09-2013, 12:29 AM   #2
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It's not just the weight, its the increase in moment of inertia which increases as the square of the wheel radius. Taller usually also means wider so you are mass at the farthest points from the center of rotation which creates the most inertia.

I ran 5.13s with 37s for a while on a non-Ripped 3.8L and it was fine off road but a bit painful on the road for my taste. If you have a 3.6L that will be a great improvement and with even a small gain in 2000-3000 RPM range from the SC you should be fine.
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Unread 12-09-2013, 09:14 AM   #3
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Agreed, it is the rotational mass that you are adding that robs power. I am guessing you have a 3.8L since you have 5.13 but along with that Ripp, you are ahead of the game when trying to push 37's on a daily. I doubt it will be a huge degradation.

I also wouldn't put KM2's. They run smaller than most other tires and do poorly in really wet and snow conditions as they have no siping. Just my .02

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Unread 12-10-2013, 02:38 AM   #4
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2012 JK Wrangler 
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I moved the posts about KM2s and siping to the Tires & Wheels section. The name of the thread is KM2s and siping? Sorry OP for the distraction.
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