leagal as in speeds being off more than a set amount can get you or anybody you let drive your vehicle on streets in trouble not to mention Emmision output.  hope any engine/trans mods you would make would be CARB compliant.  and Leaving in oil too long is NOT the only cause of sludge, oil gets slightly baked into a sludge when it removes heat causing normal sludge in your oil, however the added heat increases this sludge production.  Every engine produces sludge normally, however you can severely increase sludge buildup by increasing load on any driveline component due to the additional heat created.  normal sludge buildup is why your engine oil turns black over time and gets thicker.  normally what drips when you are about to finish draining oil is sludge which is why you should always add an engine oil flush solution to your engine according to directions given on label before changing your oil.  this should decrease the sludge buildup in your engine over time creating a prolonged engine life from stock with proper preventive maintenance.  But your engine isn't the only conponent that creates sludge in your driveline (why do you think your transmission has 1 or more filters)  your differential/limited slip also creates a surprising amount of heat and is usually forgotten about when recieving any P.M. service, things such as checking fluid levels at every engine oil change, or changing at manufac. rec. intervals. ( have you ever seen an overheated differential bearing they turn blue and burn oil into a sludge) this can be prevented by P.M. service.  they do create heat even when properly adjusted, maintained the heat does create a sludge buildu over time.  

SidewaysTim:
I have a 2004 Jeep Wrangler Unlimited with 3.73 differential gears, an automatic transmission, and 33" Superswamper SSX tires that I run about 75% of the time and stock 30" tires that I run about 25% of the time.  I've noticed that the transmission seems to shift better and more predictably when running the stock tires and seems to shifts at weird times when running the 33" tires.  Also, my speedometer is off by at least 5mph when running the 33's. Could the added diameter of the tire be making my transmission shift at weird times? Could this damage my transmission over time and is there a anything I can do to correct this without changing the gear ratio in my differentials?

simple response is yes to all of the above i'm guessing that it has delayed shifting compared to stock which maintains factory shaft speeds but at a different actual vehicle traveling speed.  

Is my rewording more to your frame of mind and understanding I understand your thinking and really do agree with you but this is more of a cost effective way of dealing with some of the problems resulting from the additional heat.  but is not a complete fix for the problem  like regearing would be however it could increase highway fuel economy by decreasing highway rpm's  

You guys are not on right page here. Where does Dodge this get this 20% stuff? Out of thin air??? It is not the same as towing because you are not turning at a lower RPM with big tires which means you are riding more on inefficient and hat making stall. Plus it now takes more HP to cruise with lift and tires and there is LESS hp available to do it with big tires and stock gears because RPM is lower AND gas motors loos torque as RPM decrease and efficiency drops so you force it to work harder at a more inefficient RPM. (this is not a low RPM tractor motor or diesel) So many are stuck of lower RPMs means better MPG when with lifts, higher RPM means more MPG because more HP is available at cruise so engine does not work as hard and it is operating more efficiently too. There will always be those that want to believe otherwise though. Believing does not make it so though.  

i;m not sure about a '04 but my uncles '94 was doing the same thing and he runs 33" Procomp xterrains. we changed the trans fluid and filter the prob was water had leaked in the trans. when he was mudding on our farm and after letting the fluid circulate good he hasnt had no prob. since  

It is not going to shift the same because it takes a higher average torque load and a lower RPM to move vehicle with bigger tires on stock gearing. Simple physics. It is just like putting taller gears in it with stock tires. The net result is lower performance and a altered shift pattern because of increase torque loads to get same effort to ground.  

you are right there but do you think 33's would make a noticeable difference? i was jus thinking it sounds like something else because he said his stocks are 30's so would 3"s make a large difference?  

10% for starters. Then add in extra drag and the loss of available HP at average road speeds because engine is turning slower and making less HP AND usually the torque is decreasing as RPM drops with a gas motor which means the power loss is even greater (HP is torque x RPM / 5252). The net result is a 15 to 20% reduction in overall performance especially cruising and towing.  

wow you have all the math figured out  

For some reason many seem to think it has little or not effect at all and that they can tune it away but in this case to do so they would have to boost power/torque 15 to 20% across RPM range just to get back to square one and have a much higher torque load on tranny in process and it is not immune to this either.  

the torque will be not actually decrease because of the fluid coupling called a torque converter however hp will suffer due to torque MULTIPLICATION created by the fins in the torque converter which actually peaks torque muliplication at peak stall because a torque converter doesn't 100% lock input to output of torque converter together otherwise if you let off the throttle the whole vehicle would throw you forward through the windshield.  

chrysler vehicle engines love low rpm's they were actually designed for torque and only list hp ratings for the public which doesn't know seat of the pants torque from top end horsepower because hp doesn't even take over the job as chief means of propelling the vehicle till 5252 engine rpm by then most chrysler vehicles with stock engines and transmissions have already shifted therefor hp is of very little effect but not completely diminished however heat production increases dramatically and yes the truth about internal vs external trans. coolers is that internal(mounted in radiator) trans coolers are way more efficient than external(mounted out of radiator)trans coolers.  the best formula for figuring out hp for this application would be to use the bhp (Brake Horse Power) formula or in other word weight lifted a distance in a given amount of time (ex. 1 m(time) moving 1 ton(weight) 5 feet in 1000revolutions(distance) is better suited to figuring exact engine horsepower production as well as horsepower available at the rear wheels this is also the way diesel engines are rated it is not calculated off torque rather the ability to move something  

dodgethis:
the torque will be not actually decrease because of the fluid coupling called a torque converter however hp will suffer due to torque MULTIPLICATION created by the fins in the torque converter which actually peaks torque muliplication at peak stall because a torque converter doesn't 100% lock input to output of torque converter together otherwise if you let off the throttle the whole vehicle would throw you forward through the windshield.

Engine torque will decrease as engine RPM decreases which means it has even less available HP and when you ride the stall as you suggest you trade off reduced output speed from converter (vs input speed) and heat generation for extra shearing and compressing of oil in converter turbines and reduced fuel efficiency.(basically when every you operate a converter under about 2300 to 2400 RPM under load you are loosing efficiency in work delivered to load vs input and the lower the RPM the greater the loss)  There is no free lunch here as you suggest and you cannot make something out of nothing but some seem to think you can. One of the failing of a automatic is that with big tires and taller gear riding the converter more lets you think all it well when it is not and then when tranny fails it is because tranny in trashy design not its application. (if you had a stick it would be a lot more obvious to you that you have a gear ratio issue)  

dodgethis:
chrysler vehicle engines love low rpm's they were actually designed for torque and only list hp ratings for the public which doesn't know seat of the pants torque from top end horsepower because hp doesn't even take over the job as chief means of propelling the vehicle till 5252 engine rpm by then most chrysler vehicles with stock engines and transmissions have already shifted therefor hp is of very little effect but not completely diminished however heat production increases dramatically and yes the truth about internal vs external trans. coolers is that internal(mounted in radiator) trans coolers are way more efficient than external(mounted out of radiator)trans coolers.  the best formula for figuring out hp for this application would be to use the bhp (Brake Horse Power) formula or in other word weight lifted a distance in a given amount of time (ex. 1 m(time) moving 1 ton(weight) 5 feet in 1000revolutions(distance) is better suited to figuring exact engine horsepower production as well as horsepower available at the rear wheels this is also the way diesel engines are rated it is not calculated off torque rather the ability to move something

I love these posts. They know just enough to be dangerous sometimes. Modern Chysler engines do not "love" low RPM's as you suggest. If they did the MPG on some on them in SUV's would not be so poor. When a engine is operated well below it torque peak, its efficiency drops and fuel usage increases per HP hr delivered to load. The last gas motor that they made that was actually good at low RPM's in a SUV was the V10. WHile it had a lower HP rating on paper than over rated Hemi it would embarrass a Hemi towing because it made torque and usable HP were you needed it at low and middle RPM's. Chysler likes these real impressive HP rating (you are right in that they are meant to impress public) but to me a engine with a 5000 RPM plus power peak and a 4000 RPM or better torque peak is worthless to me in a big SUV. You can search RV forums and find lots of Hemi towers that think it is okay a SOP to climb highway hills in second gear turning 4000 RPM and more to get engine on its torque curve. Not me, I think it is plan silly. Chysler could have had a much better SUV motor if they increase it to about a 6.3 to 6.5 and lower torque peak RPM to 3000 RPM or less. (this would have had a lower peak HP rating but a LOT more usable HP in normal SUV RPM ranges). Also on HP rating, I do not know where you get you ton work stuff but the industry standard for a HP is 33,000 ft lbs of work a minute and has been for over 100 years now. That means one HP can lift one lb 33,000 feet in a minute or lift 33,000 lbs one foot in a minute and so on. You can calculate the HP need to climb a grade at a certain weight and speed easily. There is no magi or difference between diesel HP and gas HP. The only difference is how engines power curve is match to load with proper gearing. 600 ft lbs at 1500 RPM makes and delivers the EXACT same HP as 300 FT lbs at 3000 RPM and 150 Ft Lbs at 6000 RPM. It is all in gearing engine to load and that is why semi have many speeds to keep engine at power peak. Many years ago I drove a 30 ton dump truck with a 427 and a 20 speed. Never had any trouble getting it moving in any ground and could get to highway speeds with it fully loaded without busting a gut because the gears allow you to have peak HP available basically all the time at any speed. Engine had great torque for a gas motor and you just kept it between about 2600 and 3400 when pulling hard and torque was pretty flat there. I even drove a truck with a 478 V6 in it once and it was a stump puller and its torque peaked at a mere 1400 RPM's  

A few more thing, it is HP that moves your load because torque is merely effort applied and HP is the amount of work being done or delivered. Also, on tranny cooling, in HD apps you want to run fluid through a radiator cooler then through a aux cooler. This cools it better AND it buffers cooling so when engine is running warm, tranny is still being cooled. When you place it all on tank cooler when engine get warm, tranny fries too.

Below is a link to a graph on HP needed to climb a grade

Click Here



And this next one show the relationship between torque and HP to deliver a fixed amount of HP

Click Here  

Ive a pet theory, that a vehicle will need x amount of power to accelerate a vehicle to y speed . depends on weight, but i thin the air drag will increas until either more power is needed, or all the power is being used to accelerate.
now, at cruise, you vehicle will use up X power to either cut through the air, or bludgeon its way through.
if your motor has the torque peak at or near the cruise speed of your vehicle,and its enough to give you a reserve of it to compensate for wind,hills, etc,then your gonna a more efficient vehicle than one whose power is way higher or lower than optimum. so if you drive a brick, gear it so that peak engine efficiency,torque is where you use it the most, if you have a smooth exterior, then you can play the powerband a little, sisce drag is less of a factor in the power consumption equasion. since a 4 by is by definision a brick, i had a 04 ram 2500, pretty slick by todays standards, my torque peak started good at round 28 to 3000 rpm, which makes for a great top end rush that beat so many chevys, but bad for milage, coz if it pulled like that at 1900@60mph,it would have given me enough power so i used less gas to run at that speed, = more efficency.
like snow man said if dodge increased the litres to 6.1 to 6.5 and put the power right at 1900 to 2300 it would be a monster tow rig, and way more efficient to boot  
i pulled a 16k load in my hemi powered ram, got 10 to 12 mpg with the o/d off, never heated the engine coz we ran it in a more efficient operating range. from Arizona to Corpus Christi, Texas.
the way out of ineficient bricks wasting gas is to make them slick as a car. with a low cd and a minimun frontal area to greet the wind-cg
run your auto matic inefficently directly mean that your engine is being used inefficiently, unless you match the entire set up to optimise what yuo have to where you run itmyour wasting time ,effort, and gas.
humble thoughts from a person who has driven over a million documented miles.