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Discussion Starter · #1 ·
Know this topic has been beaten to death but I run my stock '08 Rubicon as my daily and I am going to upgrade the tires. The stock KMs are load range C and weigh 48lbs. I have my eye on a set of 285/70/17 BFG KO2's but they are load range E and 58lbs each. Should I stay away?
 

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I have been running 80+ lb Pitbulls no issues for the last 4 years. The heavier tire will reduce your fuel mileage a bit but they are tougher. Reducing air pressure will smooth out the ride and produce even tire wear.
 

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Weight is not the typical problem with all E-rated tires, it is sidewall stiffness. I am also running E-rated KM2s which are one of the lightest tires and neither weight nor stiffness is a problem. I also like the E-rated tires because I can run higher air pressure for improved fuel economy and handling. Other tires like the Toyo's and Nitto's are both heavy and on the stiff side so it just depends on tire construction.
 

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I went from 285/70r17 Toyo AT2, in standard load, to 255/80r17 Coopers in E load.

The tires are stiffer and I feel it sometimes, mainly on washboard or small sharp bumps, but it's also comforting to know how tough they are and it handles much better overall. Off road they are fine and less likely to get a sidewall pinch.

You can reduce the pressure to simulate a softer tire, but there is more to it than that. You have to reduce the pressure a lot and then the tires run warmer and are less efficient. Just be ready for a slightly stiffer ride. It's no big deal.
 

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If you really want a soft ride then the E rated tires may not be the best choice. As noted by Raspy, lowering the air pressure (below 25-26 PSI) to make them compliant can cause them to run hot and eventually become damaged.
 

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Gearing changes everything, I would probably be around 11 or 12 with stock gears lol
Yes, gearing does change everything. But going 75-80 MPH in these bricks is definitely part of the problem...:)
 

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no! I had oem willys wheels/tires, and when I switched to 35" KO2's and a lift, it rides fantastic for a dd.

btw, i'm getting mid 19's on highways and low/mid 18's on street on my 35's.
Manually calculated? Or OBC (after reprogramming for tire size obv)? Thanks.
 

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If you put load range E tires on be sure to follow the wheel manufacturers PSI rating for the wheel if it is less than the tire PSI rating.
 

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Discussion Starter · #14 ·
Thank you everyone for the input. I have an 08 rubi 6 speed w 4.11s. I do ALOT of highway driving. I want to do a 33 tire. The 285 70 17s im looking at in a duratrac is a great tire, and they are d-rated which is perfect. But then i saw the new KO2 a/t from bfg and they are e-rated. I have always like bfg and im just worried about the heavier construction of the tire. The KO2 is such a new style I really want to be a bit different just worried about their weight at 58 lbs each. Stock bfg km are c rated at 48 and the duratracs are 54.
 

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Thank you everyone for the input. I have an 08 rubi 6 speed w 4.11s. I do ALOT of highway driving. I want to do a 33 tire. The 285 70 17s im looking at in a duratrac is a great tire, and they are d-rated which is perfect. But then i saw the new KO2 a/t from bfg and they are e-rated. I have always like bfg and im just worried about the heavier construction of the tire. The KO2 is such a new style I really want to be a bit different just worried about their weight at 58 lbs each. Stock bfg km are c rated at 48 and the duratracs are 54.
4 lbs is less than 10% difference between the DT and the KO2. They both have new gen hybrid AT/MT tread design and both are great tires. If you want a different tire the KO2s are new to the market and are available in limited sizes so they fit the bill but over time if they are half as popular as the KO it will change.
 

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clearly I'm doing something wrong. Our toll roads run at 75 to 80 mph...maybe that's it? Different thread I guess, sorry for the hijack
The force of aerodynamic drag (Fd) regarding an auto is the product of the drag coefficient (Cd) times the frontal area (A), multiplied by the square of the velocity. Overcoming Fd requires a propulsive force rising as a cube of velocity. An ordinary car traveling at 40 mph may require 20 horsepower to overcome aerodynamic drag, but this would rise to 160 hp at twice the speed (80 mph).*

* Horsepower to overcome aerodynamic drag

Compare the Cd, A, and CdA of a stock Wrangler to other vehicles here:

Vehicle Coefficient of Drag List - EcoModder
 

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The force of aerodynamic drag (Fd) regarding an auto is the product of the drag coefficient (Cd) times the frontal area (A), multiplied by the square of the velocity. Overcoming Fd requires a propulsive force rising as a cube of velocity. An ordinary car traveling at 40 mph may require 20 horsepower to overcome aerodynamic drag, but this would rise to 160 hp at twice the speed (80 mph).* * Horsepower to overcome aerodynamic drag Compare the Cd, A, and CdA of a stock Wrangler to other vehicles here: Vehicle Coefficient of Drag List - EcoModder
Nice! Makes sense, thanks!
 

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Discussion Starter · #19 ·
That's with a 3.6.
 
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