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?  

THE JEEPS COMPUTER SHOULD BE SET TO SHIFT AT CERTAIN RPMS FROM YOU STOCK TIRE SIZE AND THE BIGGER TIRES ARE MAKING IT HUNT FOR THE CORRECT RPM TO SHIFT. YOU COULD RECALIBRATE THE SPEEDO BUT THE ONLY WAY TO CORRECT THE SHIFT PROBLEM IS TO REGEAR IT(NO WAY ARROUND IT IF YOU DONT WANT TO HURT IT)  

papa hit it right on the nose... Your tranny doesn't like the larger tires, no electronically controlled trans does.  

What about the Superlift Truspeed?  I've been doing some reading and investigating and it seem's like this would rectify the hunting issue with the tranny?  Any expirience with this product?  

I have no exper./w the truspeed but i did read about it too and it does say it corrects the speed for tire size,but if you dont do anything w the gears youll still put unnessesary strain on the tranny and other driveline components.
now if you find the right combo for tire size and r/p it should cure the hunting problem and put your rpm's where they should be that way and youll have better power and not be lagging in that dept...373 is a good gear for stock tire size but a little doggy w/bigger meat  

I know that if you buy a computer tuner you can adjust the shift times and I think recalibrate the speed sensor for larger tires. At least that's what I did with my dad's "old" F250 SD.  

b3000boy:
I know that if you buy a computer tuner you can adjust the shift times and I think recalibrate the speed sensor for larger tires. At least that's what I did with my dad's "old" F250 SD.

This does nothing to reduce the added load and strain on tranny for big tires and stock gears. Engine now turns less RPM at same ground speed so more average torque has to be carrier by tranny and it also rides torque converter stall longer and more often and can slow bake tranny. I would venture to say that big tires and stock gear at likely the number one cause of tranny failures in 4x4's. Many seem to think it has no effect of durability or lifespan when the reality is the "HD" look for big tires actually makes your truck more "LD" with stock gears because engine and tranny has to work even harder than before even in normal driving.  

b3000boy:
I know that if you buy a computer tuner you can adjust the shift times and I think recalibrate the speed sensor for larger tires. At least that's what I did with my dad's "old" F250 SD.

SnoMan:
This does nothing to reduce the added load and strain on tranny for big tires and stock gears. Engine now turns less RPM at same ground speed so more average torque has to be carrier by tranny and it also rides torque converter stall longer and more often and can slow bake tranny. I would venture to say that big tires and stock gear at likely the number one cause of tranny failures in 4x4's. Many seem to think it has no effect of durability or lifespan when the reality is the "HD" look for big tires actually makes your truck more "LD" with stock gears because engine and tranny has to work even harder than before even in normal driving.

True.  

what about Trans coolers helping with the extra heat created this could still prolong the life of any transmission whether or not it has larger tires, such as a tow capable off road vehicle that sees street time and towing  

Cooler helps but you really need deeper gears with bigger tires as it is better to not make the extra heat to begin with. Towing with stock tires is not the same as big tires stock gear because it forces engine to work harder at a lower RPM and ride converter longer too because of a taller effective gear ratio.  

some aftermarket transmission speed adjusting adapters with a reasonable reprogramming of the computer could cause the transmission to operate closer than a hunting transmission to the better shifting and driveability of a stock transmission. But it will never completely solve the initial problem However without regearing you should do your reccomended flush services for all systems more frequently (EX. 40,000 miles VS. 50,000 miles) this would include oil changes(engine AND DIFFERENTIAL- the most abused and least likely to be maintained), transmission flushes,cooling flushes and even intake manifold cleaning services... very few people have even heard of this treatment, but engine intakes build as much carbon residue as your valves, pistons, and exhaust system recieve except it is stickier and acts like sandpaper on top of how coarse your factory intake is, (but some coarseness is needed for fuel atomization but stock setups do go a little overboard) and this service does not just clean your throttle body/carb it actually cleans the carbon from your INTAKE MANIFOLD AS WELL AS THROTTLE BODY and a top of the line cleaning service will actually clean all of intake, throttle body,and fuel injectors/carburetor jets from fuel residues. but this is only for mild tire size changes. only one to two sizes from stock if your axles are not reccomended for the tire size your trans isn't either in a stock app. with bigger tires if one part of a vehicle driveline recieves an upgrade all the rest should be reevaluated to see if it can handle the added strains from the upgrade.  

This is VERY misleading. People want to believe you can calibrate this away but you cannot. No flush or servicing is going to fix the fact that tranny has to handle more average torque AND operate at a lower average shaft speed because of taller effective gear ratio. Also you will have less available ground power/tractive effort. Simple physics here.  

towing is nearly the same as running with bigger tires strainwise on your transmission and engine however you aren't always running with the load of a trailer on being the difference.  the amount of additional heat from towing is about the same 20% as the larger tires of approx. 20% additional heat.  and heat is the major killer of transmission not the actual loads because when the trans goes into gear it is like engaging the clutch in a manual trans. the power is either transmitted or not.  it is either locked or not. And there are kits to make sure it is locked when wanted locked.  BUT THEY DO NOT SOLVE WORN OUT TRANSMISSION ISSUES!!!  that is the basic of an auto trans. the big reason an auto trans is feared are the fluid control passages in the shift body.  otherwise the auto treans is similar to a manual trans (Honda used to add a shift control device to a manual trans to make an auto trans in some earlier civics) the real difference  is the control systems manual trans use shift rods, forks,  sliding collars, and operator to select gears, an auto uses  computer(operator, fluid pressures, and solenoid controls (acting like the shift rods and forks) over surface area to press clutches that hold  the planetary gearset for a certain gear in a certain pos. that can be changed for another gear. (similar to the sliding collar moving to hold the next gear) The biggest source of heat buildup in an automatic trans. is the torque converter, the primary concern should be the torque converter handling the added strain not the transmission due to the torque converter clutch being so weak and easily damaged by slip.  which needs adressed when recalibrating computer by increasing fluid pressure to increase holding ability.  However the tcc is not even in operation until 2nd gear and the vehicle is maintaining a steady speed for a given timespan in that particular model.  

I didn't say it will completely solve the issue of strains on driveline but it will help keep you legal and I agree you will have less available power however the service schedule is adjusted to compensate for the added strain on the fluids in these systems ENGINE OIL DOESN'T JUST LUBRICATE YOUR ENGINE IT ALSO REMOVES THE HEAT FROM ALL PARTS OF YOUR ENGINE THAT IT TOUCHES AND THIS IS WHY ENGINES PRODUCE SLUDGE.  that said your service intervals need adjusted because of the added heat creating more sludge and it doesn't just happen in your engine it happens in your entire driveline cooling system, trans., differentials and even tranfer cases.  definately is a better idea to regear for the added tire size but at upwards of $1,000+ per axle to have it regeared if everything has already been removed... it isn't always within a persons budget to regear their axles and sometimes do have to live with the additional wear and lack of power of bigger tires on your driveline.  

Legal??? What are you talking about?  Also engine produce sludge when you leave oil in too long. Oil can only suspend so much dirt and byproduct and when limit is reached, sludge forms.