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Topic Review (Newest First)
08-01-2012 06:18 PM
PieFace I was going to go with 33.9 km2s, I was instructed to go bigger.
08-01-2012 05:08 PM
JEEPDON Be ready-- here is mine with the 2 1/2 max travel on 37's!!


You'll need to fill those wheel wells
08-01-2012 09:23 AM
PieFace The 2.5 X-Factor is the max travel plus upper control arms and rear trackbar. Its not listed on the RK website yet, but it is on their facebook page.

its about $1900 in steel and Im going with their RRD remote resivior shocks. I havent heard much about the shocks vs. bilstein, but I figure, if rock krawler is making them specificly for their lifts, they are probably tuned in pretty good.

Ill let you guys know in about 6 days!
08-01-2012 07:00 AM
smirak Yeah...I've been living/working in Iraq for almost 2 years now in order to afford their lifts. Can you ask if they'd give me one for free? I'd even consider putting a sticker on my Jeep

Just kidding...I'm about to pull the trigger on the 2.5 flex (initially), so I'd like to have as much info "from the source" as possible. Pics/literature/free stuff/discounts of any sort/etc...

Thanks!
07-31-2012 09:24 PM
rundm 2.5 X Factor or 3.5 X Factor? I didn't see the 2.5 on the web site. I would have been interested in having the whole set up. As it is, I ordered the 2.5 max travel system.
07-31-2012 07:57 PM
ave8er
Quote:
Originally Posted by enjerhoo View Post
Out comes my inner physics geek.

The further out you take mass from the axis of rotation, the larger the moment of inertia. The inertia increases proportional to the square of that distance. Larger inertia is larger resistance to change in velocity so it takes more energy (torque) to get the wheel turning and therefore less energy to put into spinning up the wheel, worse gas mileage & slower accelleration.

The axis of rotation is not the center of your axle (unless you have it up in the air), it is the point where the rubber hits the road. so every incremental increase in tire mass (weight) will increase inertia quadratically based on the rim diameter + the sidewall thickness.

80 lb 32" wheel has less inertia than an 80lb 33" wheel. So trying to keep the weight of the larger tire as low as possible to offset the increase in height will help the overall performance - all else being equal.
i think spinning free in the air that is all true and matters but sitting on the ground with a Jeep on top 10 pounds can't make that big of a difference... right?
07-31-2012 07:22 PM
PieFace
Quote:
Originally Posted by Frshmt View Post
That's all well and good, but it has such a miniscule difference from one 35" tire to the next. Personally, I'd rather have a tire with a strong sidewall than run the lightest tire I can find and tear a hole in it on the firs tree root or rock I hit.

I feel the same way, but when you really get to it both duratrac and km2 have a 3ply sidewall. Are you saying you would go to an E rated tire?

How do you guage sidewall toughness?
07-31-2012 07:05 PM
Frshmt
Quote:
Originally Posted by enjerhoo View Post
Out comes my inner physics geek.

The further out you take mass from the axis of rotation, the larger the moment of inertia. The inertia increases proportional to the square of that distance. Larger inertia is larger resistance to change in velocity so it takes more energy (torque) to get the wheel turning and therefore less energy to put into spinning up the wheel, worse gas mileage & slower accelleration.

The axis of rotation is not the center of your axle (unless you have it up in the air), it is the point where the rubber hits the road. so every incremental increase in tire mass (weight) will increase inertia quadratically based on the rim diameter + the sidewall thickness.

80 lb 32" wheel has less inertia than an 80lb 33" wheel. So trying to keep the weight of the larger tire as low as possible to offset the increase in height will help the overall performance - all else being equal.
That's all well and good, but it has such a miniscule difference from one 35" tire to the next. Personally, I'd rather have a tire with a strong sidewall than run the lightest tire I can find and tear a hole in it on the firs tree root or rock I hit.
07-31-2012 06:23 PM
PieFace
Quote:
Originally Posted by enjerhoo View Post
Out comes my inner physics geek.

The further out you take mass from the axis of rotation, the larger the moment of inertia. The inertia increases proportional to the square of that distance. Larger inertia is larger resistance to change in velocity so it takes more energy (torque) to get the wheel turning and therefore less energy to put into spinning up the wheel, worse gas mileage & slower accelleration.

The axis of rotation is not the center of your axle (unless you have it up in the air), it is the point where the rubber hits the road. so every incremental increase in tire mass (weight) will increase inertia quadratically based on the rim diameter + the sidewall thickness.

80 lb 32" wheel has less inertia than an 80lb 33" wheel. So trying to keep the weight of the larger tire as low as possible to offset the increase in height will help the overall performance - all else being equal.
Now you have to tackle the whole heavier and thinner vs ligher and fatter. Thinner being the less resistance than fat, while the lighter weight is better than heavy.
07-31-2012 05:38 PM
enjerhoo
Quote:
Originally Posted by Frshmt View Post
That's going to be an awesome lift, but I really don't get why so many people stress over the weight of a wheel/tire combo.
!
Out comes my inner physics geek.

The further out you take mass from the axis of rotation, the larger the moment of inertia. The inertia increases proportional to the square of that distance. Larger inertia is larger resistance to change in velocity so it takes more energy (torque) to get the wheel turning and therefore less energy to put into spinning up the wheel, worse gas mileage & slower accelleration.

The axis of rotation is not the center of your axle (unless you have it up in the air), it is the point where the rubber hits the road. so every incremental increase in tire mass (weight) will increase inertia quadratically based on the rim diameter + the sidewall thickness.

80 lb 32" wheel has less inertia than an 80lb 33" wheel. So trying to keep the weight of the larger tire as low as possible to offset the increase in height will help the overall performance - all else being equal.
07-31-2012 04:34 PM
Frshmt That's going to be an awesome lift, but I really don't get why so many people stress over the weight of a wheel/tire combo.

Good luck with everything, hope it works out like you're wanting!
07-31-2012 04:30 PM
PieFace here is a pic of the ultra crusher wheel. My goal was the maximum wheel and tire size but with the least amount of weight. I was hard pressed to find wheels that fit the bill.

Every ounce on the wheel (unsprung weight) hurts performance and I really wanted to keep the weight down. This wheel is a hair over 26lbs and the Duratrac tire in 315 is a hair under 60lbs. The total weight being about 86lbs was the best combination that I could come up with.

Do others know that TireRack mounts and balances tires for free? I was on the phone with the guy, and I was driving him crazy over the weight of the rims I was considering, and when he showed me the crushers, I thought that with the cost of the tires and shipping I was pushing my budget. I just said out loud that then I would have to mount and balance the tires and the guy stopped me in my tracks and told me they would do it for me for free, and send them balanced. $120 saved.

I asked him if he was just doing that for me, and he said that its just what they do, and when I asked that he have them balanced with all the weights on the inside he laughed at me and told me that was the only way it was done.

My jeep came from chrysler with weights on the outside of the wheels, it makes me sick to look at them. They will be off soon!
07-31-2012 04:12 PM
kristof2 Awesome! That is the lift i am planning on getting. I am looking forward to see the pictures.
07-31-2012 04:02 PM
PieFace Ultra Crusher 17x9s and duratracs in 315/70R17

Just found out that TireRack.com will send them already mounted and balanced....I was shocked to hear that. Saves me 120 bucks on mounting and balancing.

Ill let you know how good they mount and balance.

Also, the tires are too big to fit in my truck, so having them mounted and balanced and sent straight to RockKrawler works out GREAT.

Ill find a pic of the wheel and post it.
07-31-2012 03:31 PM
JEEPDON
Quote:
Originally Posted by N3M0 View Post
yes, before and after pics and lots of em!
X2
If it is anything like their Max Travel, you are going to get lots of lift!!
What are you going to run for wheels and tires??
07-31-2012 02:13 PM
N3M0 yes, before and after pics and lots of em!
07-31-2012 02:11 PM
Daniel_M
Quote:
Originally Posted by PieFace View Post
Hey Everyone,

Im making the trip to Albany this weekend to have the NEW 2.5 X-Factor Installed on our JK.

Ofcourse im bringing some friends and cameras.

Anyone have any questions they want answered at the source? Anything you want pics of?
Ask them for a full spnsorship for me.

Congratulations and nice choice in suspension! Before and after pics

-Dan
07-31-2012 02:07 PM
pluke the 2 good stuff PieFace.

Pics of the whole jeep before and after would be great!

good luck!
07-31-2012 09:34 AM
PieFace
RockKrawler this weekend!

Hey Everyone,

Im making the trip to Albany this weekend to have the NEW 2.5 X-Factor Installed on our JK.

Ofcourse im bringing some friends and cameras.

Anyone have any questions they want answered at the source? Anything you want pics of?

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