We just completed a 3,000 mile trip towing a "R-Pod" travel trailer (weight about 2,400 lbs). Our Z71 did OK as long as I kept it in third gear (about 2300 rpm at 55 -60 mph. The main factor with this trailer is that it is tall and creates a lot of wind resistance. We got between 10 and 12 mpg.
We have an 08 Z71 with the factory tow package rated at 5,000 lbs.
I am considering a tune for towing, but there must be a down side or Chevy would have tuned the Colorado at the factory. Will a tune shorten the transmission life? Or is there any other down side to a tune?
Thanks for any help

A tune will actually do better for clutch bands in the transmission as it will lessen the amount of slip. You can also increase the line pressure for quicker/firmer shifts. GM de-tuned these trucks from the factory to keep within safety ratios and warranty factors. My truck has been tuned for over 100k miles now and no issues. I have a constant load of 600+ lbs in the bed (work gear) and have gotten better fuel economy with the tune. You should also only tow in 3rd gear. 4th gear is an overdrive and will not spin the torque converter fast enough to cycle the fluid through the transmission and will thus increase internal temperature.

I was considering an R-Pod travel trailer myself due to it's size and it being relatively light weight. I figured the shape was more aerodynamic compared to the traditional shoe-box shaped trailers out there so it should have less drag.

Still not sure what the downside is for tuning - there must be some. The R-Pod is a great little trailer, it has everything in it and is very comfortable for my wife and me. We went through two snow storms and a lot of rain and we fine in the pod. If you get one, be careful where you buy it. We traveled to Ohio to a dealer there that gave us great service and a price about $6,000 lower than a Connecticut dealer.

The biggest downside to tuning is that it is reported the dealerships have a way of detecting a performance tune and can void the powertrain warranty.

Other than that, there really isn't a downside to a good proper tune performance or reliability-wise.

So always tow in 3rd gear?
I am in Atlanta and towing a small camper 1800 miles to Yellowstone in June. Had planned to change original transmission fluid due to abnormal stress on the transmission.
Everything else is stock and original, fluids, spark plgs, etc...Nothing but oil changes, filters, and brake job for 69K.
Any other suggestions before my trip to increaseperformance, mpg, etc...?

From the manual

Duh, from the manual Why didn't I think of that?
Hope someone answers me on the changing of the transmission fluid idea. Don't want to do it $$$$$
if not needed or of no benefit. Same ATF for 69K.

HerbLindblom: Down side to tuning is cost and it could void your warranty. Done correctly, it could provide better power and towing capabilities. The more aggressive you go, the more power you get BUT also reduce the amount of conservatism and comfort (soft shifting) provided by the factory settings. I have had warranty work done with my tune....although I always load the stock tune back in before my visit.

high tech.: Since you are towing and are over 50k, I would change the transmission, axles and transfer case fluids. I change mine every 50k at a minimum. Also do not forget the brake and power steering fluids. I change mind every 2 years or 24k - which ever comes first. I would also recommend a tranny cooler - it does a tranny good. I do not do much towing but still have a tranny cooler on mine. Also have a power steering cooler on mine but that is because of the oversized tires.