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Discussion Starter · #1 ·
I currently have an '09 JKU with 18" stock tires/wheels and 3.73 gears (auto). My stock 18" spare weighs 69 lbs on the bathroom scale. I've decided to go with the GY Duratracs, although I haven't decided yet if I'm going to go the 15" or 17" route. I don't want to start another 15" vs. 17" debate thread -- I've read all those. I've also read all the threads about the impact of unsprung weight.

From what I've found, total weight per corner ranges from 68-74+ lbs for the popular 33x12.5x15 Duratrac (depending on the weight of the desired wheel) and 77-84+ lbs for the LT285/70R17 (again depending on the wheel). This puts the lightest 17" wheel paired with the 285s at 8 lbs per corner more than my current setup. So my question is how much more weight per corner is too much? I know that's subjective, but I'd still appreciate some input. This is my DD and work is 50 miles round trip, so I don't want to totally tank my performance. Thanks! :thumb:
 

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Discussion Starter · #2 ·
*bump* Anyone?

I'm ready to pull the trigger on new tires/wheels but I like to hear from others running 17" wheels with duratracs on '07-'11 JKs with auto and 3.73 gears.
 

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The general rule of thumb is that 10 lbs. of unsprung weight is like hauling 100 lbs. of weight in the back of vehicle. So, if you end up with wheels/tires that are 10 lbs. heavier per corner...that's like putting 400 lbs. of bricks in your Jeep and driving around. YES it's going to drop your fuel economy by around 1-1.5 MPGs and it's going to increase your stopping distance and acceleration time.

The fact that the 33x12.50-15 version on MB wheels weighs less than a factory Rubicon wheel/tire is fantastic for keeping stock driving characteristics in check.
 

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From the drivers seat, 10 lbs per corner unsprung is hard to feel, especially in a jeep. BTW, this is more about "rotating" weight, which is more critical than unsprung weight. However there is a lot of misinformation out there related to rotating weight. I've heard "10:1..." compared to sprung weight thrown around regularly, but the real difference is closer to 2:1.

Edit: didn't see the above reply! There are equations to calculate the affect... found on many autox/road race forums.

When I raced cars I went from 17 lb wheels to 10 lb wheels (same race rubber), but the real performance difference was pretty slight... and that was in a 2100 lb car.
 

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I have a set of Michelin XML 395/85R20's I am mounting on Hutchinson Military beadlockers. Tire/Rim tips the scales at 300lbs. Each.


So my question is how much more weight per corner is too much?

I'll let you know. :rofl:
 
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