I am pulling a travel trailer that weighs somewhere around 2500 pounds. I pulled it for the first time this weekend and it pulled very nicely in the 60 to 65 mph range. I pulled the trailer in D. The transmission only downshifted when I would start climbing fairly large hills, on average, probably once every 20 miles or so. I tried pulling in 3rd first, and it just felt like the truck was running too much rpm. Any thoughts on best methods for towing?

 

If you are going to be climbing alot of hills or varying your speed alot you want to tow in 3rd.
If it will be flat expressway then 4th is fine.
65 in 3rd is fine, just dont go any faster than that.
You just dont want the transmission shifting to much because it will overheat and wear out the clutches faster.

 

That's what I was thinking. So as long as it's not downshifting frequently, it should be ok right?

 

Yes, as long as it is not shifting to much you'll be fine.
The slower you go the less it will want to downshift, so set the cruise in the 60-65 range and if you see a hill coming move the gear shift into 3rd, once you crest the hill go back into 4th.
Now if you are going to be gong down a really long hill then stay in 3rd and use engine braking to keep the brakes from overheating.

 

Don't them there D-II have a sport mode on the tranny ?
I would just run it in sport and drive.

 

Would sport mode make it want to downshift more agressively?

 

Sport mode is going to make it downshift more, dont use sport mode for towing.
The trick is to keep the trans from shifting as much as possible, when under load it is hard on the trans for it to constantly downshift.
To much shifting will cause the trans to heat up, excessive heat will wear out the fluid faster.
The more it shifts the more it wears out.