TheDirtman

If we were wheeling and you got stuck I could likely driver over you to keep going. You would not have a chance to drive over me in the same situation.
You need to look at the tires like a lever or ramp and it should answer your question with your background knowledge of physics.

rob_engineer

However, it also takes more torque to turn the bigger tires so less power is delivered where the rubber hits the road. I sense some sarcasm in your response. Didn't really add much value to my question.

jedg

hahaha.. I took his response as humor... driving over you.. hehehe...

What he said though.. another way to look at it. With his larger tires (40"), the mid-point of his axle is at 20" (not counting airing down)... the midpoint of your tire (say you're running the Rubicon 32") is 16". Now approach a step ledge that is 18". He will crawl over that ledge MUCH easier because his tires will still be acting like a ramp (as he put it). With your tires, the jeep has to climb UP then over... it has to overcome that 2" of vertical climb first.

Another point. His tires are likely 13.50" wide... (35" inch tires typically 12.50).. this gives a greater surface area for traction when you do need to climb up a surface. To fit those widths and diameters you need the lift.

Like he said, the lift is to fit the tires.

EDIT - your point about torque is valid, but that's overcome by gearing (which he also pointed out).

That said, I'm running a 6.0L L96 and I can tell you that sometimes that power is a disadvantage. I've had more than a few times where a fellow still running the 3.8L drove right over an obstacle easier than I did because I was delivering too much power to the tires and would break traction when they held theirs.

TheDirtman

That is the purpose of proper gearing, to restore proper torque to the tires and having 4 low in the transfer case. Larger tires run in a flatter arc or lower angle when coming in contact with an obstacle.
Taller tires will also help with approach and decline angles as well as break over. Taller tires will allow you to climb bigger rocks as the center of the wheel is higher. A bigger tire with flatter arc will have more contact area on a vertical surface. Its all simple physics when you break it down. This is easier to explain with pictures then with text. Once you see it on paper it really make sense.

jadmt

think of a bicycle. If you are riding a bicycle with 20" tires and you come to a ledge that is over say 10" tall you will endo. If you are on a 29er you simple just roll over the ledge with no drama. bigger tires roll over ledges, downed logs, big rocks, ruts much easier than smaller tires. also you will high center and you will turtle with all 4 tires off the ground. again if just doing forest service type roads stock is fine if you are going to do the Rubicon trail or Golden Spike trail you will beat the crap out of your stock jeep. the lo range transfer case makes up for the extra torq needed to turn bigger tires. Power loss from bigger tires comes more at highway speed. stock jeeps generally get better mpg and are easier to get into. I always hear the argument that my stock jeep can go where yours does but then they see where we go and change their minds. Stock jeeps with same engine/gearing etc will accelerate faster and stop better.

TheDirtman

Some of the advantages a stock jeep over a lifted big tire jeep is better mpg, less maintenance, access to insurance, you save the money, and parking in tight spots. If you wheel a stock may have the advantage in some situations due to obstacles like trees. I know in the past with the width I am I had to pick an alternate route in some wooded trails at Redbird, IN

rob_engineer

Thanks guys. Getting some good feedback. I like the post about riding a bicycle over the curb with different size tires. Why did I start this post? A coworker recently upgraded his Rubicon with lift, tires, flat fenders, shocks, etc. He did it the right way. I now feel inferior when I park next to him. I want to make myself feel better about my stock JKU.

jedg

Well shoot, I guess I'll give you the grown up answer (even though I don't want to). If your jeep is meeting your needs, then hold what you got.

rob_engineer

My daughters boyfriend has a 2012 that was not done right. Has the lift and big tires, but 3.21 gears. I rode in the back the other day. Felt like the back end was disconnected. Wobbly, bouncy, noisy. I'll take my stock setup over his any day.

Blizz

Jeeps are an expensive way to measure your dick...