[bunkers]

This weekend, I towed my 22' Hybrid travel trailer [ around 6000 lbs loaded ] between Colorado Springs and Castle Rock, CO ... up over 8000' Monument Hill -- and D worked fine for most of it.

But for something like heading up into the rockies on I-70 up floyd hill ... I switch to 4th and even 3rd just to keep it at 55. I did 4th and a little 3rd over the 11,000 ft pass into leadville ... and the Titan held 50-55 and I was happy.

I like to keep the rpms around 2000 or less for best mileage, but if I start going slower in 'D' or shifting occurs, then its time for '4' instead. I've never seen my tranny temp go up at all yet, not even towing a 20 percent grade with the trailer.

I've also noticed that once I got out of Colorado and into Nebraska, the elevation drop gave me so much more power I almost never shifted at all unless I had a strong headwind. I've often wondered what the difference between D and 4 would be and I swear I towed most of last summer using 4 by accident ... and it almost seemed like I got better mileage in 4 than I do in D ... is that possible? These days I've being doing 'D' cause I like the lower rpms and if it holds it up the hill, I figure it's capable of it. Around the top of manument hill, I think I had to throw it into '4' for a minute, just to maintain 55-60, which is all I do towing for safety and mileage reasons.