Getting ready to order my new duramax have the option of 18's or 20's and 3.73 or 4.10 rear ends

thinking that 20's and the 4.10 might be best, gives me the option of bigger tires

any thoughts?

If you plan to tow and get bigger tires I'd definitely go with the lower option.

Buck

I would stick with the 18's because a bigger selection of tires. Either ratio will work depending on weight your towing.

Wannabe

I have been hesitating for a couple of weeks on this, which is not my style. I know that when I went from stock 16's to 17's with slightly taller tires on my 06 duramax I could feel it in the ride and even acceleration.

All the Fords I have ridden in with 20's have a lousy ride in comparison to my current truck.

At the end of the 200k miles I will likely put on I think ride will be the more important factor. I know it is for my wife.

18's and the 4.10 rear end seems to be the way to go now that I look at the tire prices and selection, thanks

4.10's might be overkill. I have them in my Ford diesel and while great for towing, I think they would be too much for daily driving unless you drive 60-65 mph. If this is a daily driver, I would seriously consider 3.73 unless the 4.10 increased listed towing capacity.

Thinking more on it. Dmax get good fuel economy as long as you don't top 2K rpm. My 06 runs 80mph at 1900 or so rpm with the 3:73 and 32.65diameter tires. 4:10 would put me at 2100 rpm for the same speed.

Guess the 18's and 3.73 makes the most sense if not the most style.

I do pull equipment on occasion but never lacked for pulling power since we don't have much in the way of big hills anywhere near here.

Checked my numbers here http://tech.oldsgmail.com/axle_RPM.php

Just checked the GMC website to confirm nothing has changed with the new 2015 model.
http://www.gmc.com/sierra-2500hd-pic...abilities.html

Unless you have access to some special order that is not listed, Duramax diesel is standard and exclusive to 3.73. Gas has the 4.10.
Delima solved

Personally, there is so much torque on tap, unless you are extensively towing at the upper end of ratings, I see no need for 4.10 with anything that would fit under stock/leveled suspension.

As a general assumption, 20's are for posers. The side wall is too short on a non-lifted body. The wheel will grind on a curb or even in the mild rough. Lift the body and all safe tow ratings are out the window.

I was suprised at the 4:10, dealer is a fleet dealer and said they could order it. I have not verified it anywhere. Does not matter, have decided to go with 18's 3:73 z71 and the all terrain tires. Thanks for all the input.

Sounds good.

You might check what tires they are using as "All Terrain". My 2008 17" came with Bridgestone Duravis that were AWFUL.
Might be worth not taking the upcharge or negotiating to replace before delivery.

Congrats on the new truck.
Local dealer is offering an overnight test drive of a new truck with a wash, inside cleaning and trade estimate of your current truck.
The 2015 increased CC size and front suspension is attractive and I may take the test drive to get cleanup but DEF and NO $850 payment are telling me "What you have got is pretty good"

Go with the cheapest setup and upgrade to aftermarket. ALL of the factory wheel setups are quite narrow to meet fuel mileage requirements.
Going with aftermarket (capacity correct) setups with an 8, 9, or 10 inch wide wheel will drastically improve towing stability on ANY of the trucks.