Towing a travel trailer with 3.08 axle ratio or 3.42
 

I am planning on getting a 2 year old suburban this year. All the ones I am seeing have a 3.08 axle ratio. I can't find a 2 year old one with a max trailering package or a 3.42 axle ratio. I also plan to get a travel trailer that weighs about 6,000 lbs. With my family and some equipment, my load will be about 7500 lbs. Am I really going to regret not having the 3.42 axle ratio?

You can get by with a 3.42 but better would be 3.73.ratio IMO

The new Suburbans, as far as I can see, don't even come with at 3.73 option. You can only select the max trailering package to get the 3.42. All the 2 year old Suburbans I can find, have 3.08. It seems like I have to buy new to get the 3.42 ratio. But, I would have to spend $15,000 or so more just to get it. My question is it worth it? It seems to me I can get by with a 3.08 and towing 7,500 lbs.

No one in my day would touch a 3.08 for HD use. Its all about the 2025 CAFE fuel mileage standards. Funny but I think a 3.08 axle ratio would get WORSE gas mileage while towing. In fact I would like Chevy/GM to offer a 3.55 ratio option. Also put an air-cooler for your automatic on this. It will last much longer if you do, along with more frequent oil changes. No spending 15K changing ratios on a 4x4 is too expensive.

Ok, So if I understand correctly, the 3.08 will cost me more on fuel, and that is the big difference in affect between the axle ratios? And, this is because the engine will have to run at higher RPMs to get the load? Other than that, I shouldn't have a concern?

And, since it doesn't have the trailering package on it, I will need to get
- a cooler for the transmission
- a trailer brake

A 3.08 ratio is a high ratio for a pickup or other non-light car, whereas the lower 3.42, 3.73 and a 4.10 ratios will allow the motor to rev up to higher RPM's and torque range, so that will call for not using overdrive .
Yeah, your transmission will be under a heavy load so the fluid will get very hot thus the air-cooler will help keep the temps down. The transmission cooler in the radiator will not be enough. Also keeping it out of OD on flat and upgrades, you could use it fine on a downhill grade to save some fuel. Yeah you have to have trailer brakes over a certain weight or GVWR.

We don't know your experience with equipment and towing. Suggest you go somewhere where someone has a trailer hooked up similar to what you want and offer to pay them if needed to let you ride along on a short trip to see what it is like with a similar vehicle. Where you will be towing (state) and distance expected makes a lot of difference too. Don't forget, synthetic fluids everywhere. *BW*

7500 lbs is a lot of trailer for a half-ton Suburban. Too much, in my opinion. You'll likely be over on your rear axle weight and your payload. If you're planning short trips, it might not be a problem, but if you intend cross-country treks, you might want to buy a heavier-duty tow vehicle.

I call the 3.08 the "soccer mom" axle ratio. And honestly, 3.42 isn't much better. CAFE and towing trailers are mutually exclusive.

Agreed. 3/4 ton would be better with a 3.73 or 4.10 axle ratio. GM is the only manufacturer of the 3.42 axle ratio, instead of a 3.55. Be fine in a pickup with lighter loads, but not for anything more.

I pull a 5800 (dry weight) travel trailer with my Suburban. My weight's not far off from yours. I think you should consider a 3/4 ton unless you're like me and don't mind going slow sometimes. The 5.3, 4L60e, 3.08 gearing is not the best package for towing. The 5.3 needs to be allowed to rev when pulling hills/mountains. I figure my ready to go weight at 6800, but it's probably less. The steepest climb I have made was up Black Mountain (7.5 grade) and I went up about 50MPH, 3300-ish RPMs all the way to the top, AC running, etc.. It did fine and I was passing the semi trucks. Since mine is a daily driver I will keep it and live with it breathing hard at times when towing. I need the large air conditioned space of the Suburban. The day we pulled the RV up Black Mountain it was very hot outside. The temp needle barely moved. If you're under your tow weight rating you should be fine but, don't think you're going to be in the left lane running 75MPH without a care in the world. You'll be in the right lane chillin at the speed limit (or less). Get you WD hitch set up by a professional. That will make a HUGE difference.

Edit: Also, when towing I keep it out of overdrive and I don't allow it to hunt for gears. When pulling uphill I manually pull it down to keep the RPMs up. Letting it hunt for gears gets the transmission fluid hot. I also added a transmission cooler (in addition to the factory tow package) and SumoSupersprings. The SumoSupersprings keep it from squatting in the rear so it rides flat and stable. They are easy to install.