Please explain like I am a 5 year old. New Tires, Gas Mileage drop.

wrangster

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i havent noticed any detriment to my braking. I also dont drive my jeep like sports car either. Upgrading the brakes is not cheap and not worth it imo.
That's ok but your braking will never match that of stock. We have engineers for a reason!



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wheels082

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I put on a lift and 315 STT Pro's and lost about 5 MPG on my JLU Sport. I used a Superchips tuner to correct tire size.
 

mgroeger

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OK, I need some advice as well.
We just put on D44s with 4.10s in them and were already running the stock Rubi 33" tires. We used our Tazer mini to program in the new 4.10 gears and also the 33" tires. We have the 8 speed tranny.
The first thing I noticed is that this will launch off the line like a rocket ship and you can do fun burnouts as well :)
There are two things I am seeing on a serious note that I would value any input on.

First - I noticed that it barely stays in 1st gear and goes into 8th gear on roads that it would never have when I was running the stock 3.45 gears. With the stock Sahara gears and the 33" Rubi tires 8th gear only came in to play on open highway, 74 MPH and no touching the pedal. In other words... 8th wasn't used much. Now it's used all the time.

Second - I noticed it down shifts much harder than before. 1st and 2nd gear are not stayed in for long when speeding up but when slowing down I noticed a more aggressive down shift from 4th into 3rd, etc... The only person I know who went to D44s with 4.10s has a stick so I don't know if this is "normal" for the auto.

The Tazer allows almost any imaginable tire size to be put in... 33.1, 33.2, etc... should I play around with that to get smoother shift points?
 

iznthesky

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Driving habits aside.....the “Weight” of the rolling mass....(your wheel & tire combination) has the biggest impact on performance over almost any other modification on the vehicle. If you added 15-20 pounds to the weight of each wheel.....it significantly affects the performance. If you added double that weight (weight of an additional passenger) to the Jeep....its performance would not be as effected...compared to adding weight to the wheels.

Bigger wheels & Tires = heavier
Heavier wheel/ tire combination requires more energy to move = less MPG

Bigger wheel / tires = GOOD LOOKING Jeep and you get more Smiles per gallon.
I’d consider that a good trade off. Nothing is free.
 

mgroeger

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Driving habits aside.....the “Weight” of the rolling mass....(your wheel & tire combination) has the biggest impact on performance over almost any other modification on the vehicle. If you added 15-20 pounds to the weight of each wheel.....it significantly affects the performance. If you added double that weight (weight of an additional passenger) to the Jeep....its performance would not be as effected...compared to adding weight to the wheels.

Bigger wheels & Tires = heavier
Heavier wheel/ tire combination requires more energy to move = less MPG

Bigger wheel / tires = GOOD LOOKING Jeep and you get more Smiles per gallon.
I’d consider that a good trade off. Nothing is free.
ANy chance you have insight on what I posted? Thanks in advance :)
 

TCogs1

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OK, I need some advice as well.
We just put on D44s with 4.10s in them and were already running the stock Rubi 33" tires. We used our Tazer mini to program in the new 4.10 gears and also the 33" tires. We have the 8 speed tranny.
The first thing I noticed is that this will launch off the line like a rocket ship and you can do fun burnouts as well :)
There are two things I am seeing on a serious note that I would value any input on.

First - I noticed that it barely stays in 1st gear and goes into 8th gear on roads that it would never have when I was running the stock 3.45 gears. With the stock Sahara gears and the 33" Rubi tires 8th gear only came in to play on open highway, 74 MPH and no touching the pedal. In other words... 8th wasn't used much. Now it's used all the time.

Second - I noticed it down shifts much harder than before. 1st and 2nd gear are not stayed in for long when speeding up but when slowing down I noticed a more aggressive down shift from 4th into 3rd, etc... The only person I know who went to D44s with 4.10s has a stick so I don't know if this is "normal" for the auto.

The Tazer allows almost any imaginable tire size to be put in... 33.1, 33.2, etc... should I play around with that to get smoother shift points?
My 2 cents - experience:

The JL software is quite sophisticated and it has machine learning algorithms built in (thus no tow - haul mode). I would take both batteries off line for 10 mins - 30mins.. and it will reset. Then drive it with the loads you want and style you want consistently for a day or so and unless the tazer is doing some resets it should settle down.

Example, when I tow my trailer for 8-16 hours to and from the sierras.. my shift points stay pretty high at mid throttle, after I take the trailer off, then a week later its back to normal shift points. I sure there is a Jeep software engineer reading this and smiling.. He-she can not opine...for obvious reasons (lawyers).

Another example is I swap my 37's and stock tires between trails and highway drives to save MPG and loss soft Maxxis creepy rubber.. the computer does not like that much, speed matching and shift points change there as well.. But I learned to use manual mode a lot more, so it s moot point for me..

hope that helps..

TC
 

jdubya421

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OK, I need some advice as well.
We just put on D44s with 4.10s in them and were already running the stock Rubi 33" tires. We used our Tazer mini to program in the new 4.10 gears and also the 33" tires. We have the 8 speed tranny.
The first thing I noticed is that this will launch off the line like a rocket ship and you can do fun burnouts as well :)
There are two things I am seeing on a serious note that I would value any input on.

First - I noticed that it barely stays in 1st gear and goes into 8th gear on roads that it would never have when I was running the stock 3.45 gears. With the stock Sahara gears and the 33" Rubi tires 8th gear only came in to play on open highway, 74 MPH and no touching the pedal. In other words... 8th wasn't used much. Now it's used all the time.

Second - I noticed it down shifts much harder than before. 1st and 2nd gear are not stayed in for long when speeding up but when slowing down I noticed a more aggressive down shift from 4th into 3rd, etc... The only person I know who went to D44s with 4.10s has a stick so I don't know if this is "normal" for the auto.

The Tazer allows almost any imaginable tire size to be put in... 33.1, 33.2, etc... should I play around with that to get smoother shift points?
8th gear is being used more because you are at a higher RPM because of the 4.10 gearing. The 3.6 likes to be around 2-2.2k rpm for optimum performance. With 33s, at 74, with 3.45s you are at 1742 rpm - with 4.10s you're at 2070. The 4.10 gearing is really what you need for 33s and is probably why sports and saharas don't come with 33s.
 

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I made note of a few things while on a 3 hour trip mostly flat areas during interstate travel. (2Dr Sport, 2.0L Auto, 305/65/17 tires and re cal of speedo)
At 75 mph average MPG = 12-13
At 70 mph = 15-16
At 65 mph = 18-19
At 55 mph= 21-22

MPG significantly decreases above 70 mph. Using cruise as much as possible helps.
Adaptive learning of the Auto also gradually adjusts to higher rpm shift points when you put your foot into it often. Higher rpm = lower mpg. At 65 mph with cruise on my rpm is in the 1600 rpm range in 8th gear. I also use cruise even in 25-35 zone and gradually increase speed into higher zones using the cruise buttons to gradually increase speed.
 
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jeepingib

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I made note of a few things while on a 3 hour trip mostly flat areas during interstate travel. (2Dr Sport, 2.0L Auto, 305/65/17 tires and re cal of speedo)
At 75 mph average MPG = 12-13
At 70 mph = 15-16
At 65 mph = 18-19
At 55 mph= 21-22

MPG significantly decreases above 70 mph.
We have the aerodynamic efficiency of a dump truck.
 

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When I need to think about this subject in simplistic terms, my mind tends to go straight to the bicycle. Specifically ten-speed vs early mountain bikes that weigh a ton. Just about everyone has some sort of idea behind the amount of force required to get a lighter bike rolling compared to a heavier one.
 

                           













































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