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Old 10-14-2015, 10:53 AM
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3.8L Engine 34x10.5-17 or 285/75-17

I've got a 2.5" lift and still have (and am keeping) stock flares and bumpers.

Most notably, I have the 3.8L JKU Rubicon and am looking for advice as to which of these wheel & tire combinations will leave me better engine performance?

Is there a notable weight and rolling resistance difference between these tires?

I like the "pizza" look but unsure what I gain and lose between these two sizes with respect to my 3.8L engine.

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Old 10-14-2015, 12:09 PM   #2

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not sure what 285/75-17 you are planning on using but generally that is going to be a heavier tire and also taller. the 34x10.5-17 is most likely going to be a KO2 as not sure who else makes that size. The KO2 in that size is really pretty light. I measured one at 52lbs. I know my 285/75-17 toyos were considerably heavier and taller so based on that the 34's will be more spunky.

I switch back and forth between my Toyo 35's that are within .25" of the 285 toyos for height and a few pounds in weight and when I put the KO2's on I feel like I turbo charged my 3.6L. strange thing is mpg is identical with either set up.

2018 Gobi Recon unlimited W/Mopar 2" lift coils combined with RK rear coils wedges, TF lower control arms, rear TF monster track bar and rear track bar bracket and Falcon 3.1 shocks, Cooper ST Maxx 315/75-17 on AEV Salta rims, Grabars, RE gas skid tank, mopar head liner, Warn VR10 and Maximus3 winch plate.
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Old 10-14-2015, 11:09 PM
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Great reply, thanks. After reading about the KO2 lightness I thought my mind was made up but then with the mpg being the same I am confused all over again!

Any 3.8L engine experiences?
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