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aldo98229

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I have the 8-speed auto. Don't get me wrong, it's not a dog, just noticeable. I may just be too sensitive; I can certainly live with it. I'm a bit unclear how the shift points can be changed; I don't see that option on my Tazer.
When you adjust for tire size, the system automatically adjusts the transmission shift points.
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I would regear.
 
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How close do you need to be on the speedo to be considered acceptable? I'm around 1 mph above indicated, (according to GPS); the increments on the Tazer are not really finely adjustable. I have 35" K02's.
 

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cripton805

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How close do you need to be on the speedo to be considered acceptable? I'm around 1 mph above indicated, (according to GPS); the increments on the Tazer are not really finely adjustable. I have 35" K02's.
As long as you updated it according to the wheel / tire size. It holds the gears properly instead of down or up shifting late or early.
 

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Question...does Jeep calibrate wheel size based on approx. size or actual, for example, XR package has "35s" but they are closer to 34" in actual height.
 

J0E

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What you're feeling is not weight. It's rotational mass. The engine, gearing, and transmission shift points are specifically made for the stock tire / wheel size.

You need to re-gear your diff and update the transmission shift points.
It's not rotational mass. It's the net ratio has changed. The increased rotational inertia of the wheel-tire combo is insignificant compared to the mass of the vehicle and the changed drive ratio.
 

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jhackathorne

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I'm running the Pulsar XT from Superchips and can feel a difference when I use it versus set to stock. It has Stock to Level 5 adjustment.
 

cripton805

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It's not rotational mass. It's the net ratio has changed. The increased rotational inertia of the wheel-tire combo is insignificant compared to the mass of the vehicle and the changed drive ratio.
It's actually both. If you had the same size wheel / tire. The weight went up 40lbs per wheel. It makes a huge difference on a wheel vs. in the jeep itself.
 

J0E

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It's actually both. If you had the same size wheel / tire. The weight went up 40lbs per wheel. It makes a huge difference on a wheel vs. in the jeep itself.
Not a measurable difference. On a dragster yes. And it's not just the mass, it's where the mass is at. Hard to understand if you haven't take physics and don't understand integration. The sum of the products of the masses of the particles by the squares of their distances from the axis is ∑miri2. This is the moment of inertia or rotational inertia and is denoted by I.

OP hasn't even quantified perf reduction. Tall skinny 35's, lighter than stock, would show a measurable drop in 0 to 60.

Going from stock 33" KO2s to 37" KM3s, the biggest difference I noticed is previously I could crawl vertical in M1 at idle, now I need 1,200 RPM to go vertical. That's nothing to do with increased mass or rotational inertia, it's the effective gearing.
 
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jthoms1

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How close do you need to be on the speedo to be considered acceptable? I'm around 1 mph above indicated, (according to GPS); the increments on the Tazer are not really finely adjustable. I have 35" K02's.
Did you measure the actual tire size with a tape? That gets it dialed in pretty well. With that said 1 mph is fine.
 

cripton805

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Not a measurable difference. On a dragster yes. And it's not just the mass, it's where the mass is at. Hard to understand if you haven't take physics and don't understand integration. The sum of the products of the masses of the particles by the squares of their distances from the axis is ∑miri2. This is the moment of inertia or rotational inertia and is denoted by I.

OP hasn't even quantified perf reduction. Tall skinny 35's, lighter than stock, would show a measurable drop in 0 to 60.

Going from stock 33" KO2s to 37" KM3s, the biggest difference I noticed is previously I could crawl vertical in M1 at idle, now I need 1,200 RPM to go vertical. That's nothing to do with increased mass or rotational inertia, it's the effective gearing.
I see your point, but he never mentioned crawling. He's talking about sluggish performance in general. So, yes, you are not wrong. Gearing will help. I've had three different Jeeps, different gears, and different wheel / tire. It's both the weight and size of the wheel / tire. I was trying to keep it in simple terms. I'm going to assume this isn't a dedicated rock crawler. It's going to be used on the street, hwy, and offroad.
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