09 sierra 6 inch lift 35" tires with gears towing travel trailer

[par149]

First time posting on here but ive been reading threads for years. Just thought I'd share my experience and hopefully help some folks out. I have a 2009 gmc sierra with 5.3 hd towing package with tranny cooler, engine cooler etc. 3.42 gears stock. 6 speed tranny. supposed to pull like 9500 lbs. it has a 6 inch lift with 35's, stock ,motor other than exhaust and a programmer. I purchased a 3900 lb 24 foot travel trailer to camp with the family. I pulled it from the valley in phoenix up north, approx. 2 hour drive with about 5000 ft elevation change. IT PULLED TERRIBLE!!! I was in second gear at 4700 rpm's trying to stay above 45 mph!! My tranny and engine temps got close to 240F at a couple points. So needless to say, the second I got home I called my local gear shop and had 4.10's put in it to hopefully help with the issue. I'm still in my break in period for the gears, but its already noticeable how much better it drives just around town. That being said, I do drive like an old man, with stock gears I was around 15.5 mpg and now im around 14.5, I drive mostly around town with some freeway but not a ton. Ill update the thread when I pull the trailer again next weekend.

[efritz]

Most people overlook gears when adding bigger tires, but they are very important!