We just purchased a 2015 Sierra Denali HD 2500 truck with Duramax/Allison. Love the truck! It is our daily driver AND we will be towing a 2016 Airstream 30' Flying Cloud. Airstream in this photo is, I believe, about a 27':We have been thinking of upsizing the 18" wheels and tires to 20" wheels and slightly beefier All Terrain tires (Nitto Terra Grapplers). This upsizing would also involve a "leveling kit" which raises the front of the truck 1 1/2". The stock truck sits at a bit of a rake.Is the rake of the truck intended to counter the tongue weight in the rear when towing?Are the stock wheels and tires much better for towing with than the upsized wheel/tire combination that we're considering?Would going with the upsized wheels and tires be a bad idea, with regard to towing?Moderator edit to re-size picture to forum recommended limit of 640px maximum width.

I don't know why you would want to make that change? Other than looks, I see no advantage. The 20s would likely ride rougher, and cost more. Those 18s are nice looking.To each his own, but would be a waste of money IMO.Jerry

By going with a larger wheel/tire you will be effectively raising your gear ratio. 3.73 may become more like 3.42 or 4.10 may become more like 3.73. Trucks computer may need reprogramming as well. Why change? Looks awesome as it is. Unless it's a macho thing....

If you just want to I think it wouldn't make that much difference. I really don't see any benefit in terms of towing. You have more than enough truck for that trailer. On a 2500 it should have E rated tires to begin with. The only beefing up you would gain would be a more aggressive tread design. Going for mud grips? My trailer is longer and heavier than yours and I only air my tires to 70lbs and it keeps the same footprint as when it has no load on it. I see nothing to gain but negatives unless you just prefer the look.

I would talk with your truck manufacturer/dealer first. I've seen other new truck owners say their trucks frame warranty was voided because a lift was added. You are modifying your truck chassis.... so be aware. Now having said that I see in GM online ordering guide the 2500 does have 20" wheels and tires with certain options. Again see your dealer.

As far as towing, you would not gain any benefits. In the long run it's your vehicle, have fun with it.

New Sierra Denali HD 2500 - upsizing stock tires/wheels?

N-Trouble
Explorer
Apr 28, 2015
I run 305/55/20's Mickey Thompson ATZ P3s on my 2012 Dmax with factory 20s and it rides really nice. Plenty of rubber between rim and road. Prior truck was a 2002 2500HD with 285's on 16" rims and they rode about the same. Both trucks had Bilstein shocks and the T-bars MILDLY cranked (5-6turns).
Grit_dog
Navigator
Apr 28, 2015
Or you can just slap some 20s on it and not worry about a thing. If the tire you want/get rubs at steering lock then either trim a little plastic or level the front by cranking the torsion keys a bit or getting new torsion keys.
The mph difference in 1-2" taller tire will not require you to reprogram anything but you'll be going a few mph faster than indicated on the speedo at hiway speeds.
Truck will run fine, tow fine, handle fine. May lose minor fuel mileage going to the grapplers. Like 1/2 mpg.
DHart
Explorer
Apr 28, 2015
Yes, we're sticking with the stock 18"s and the stock Wrangler SRs for now.

When the time comes to replace the tires, we will closely evaluate the options. I agree that 18"s with tires having more sidewall is the way to go.
camperforlife
Explorer
Apr 28, 2015
MPond wrote:
camperforlife wrote:
N-Trouble wrote:
camperforlife wrote:
Nice truck. My 03 Sierra had factory 20's. Loved the looks, hated the handling. My 11 Sierra has the 18's and I'll never go back to the 20's regardless of good they look.

GM never made 20's in 03... Doubt it was due to the wheels.******ride on the 03 was more likely due to over cranking the T-bars and overextending the shocks. Very common mistake amongst GM owners. With the right tire your not going to feel much of a difference in ride between 18" and 20" rims.

You and the tire dealers thought the same thing. I've argued before to the nay sayers that GM offered 20's in '03. I bought it new, it was factory and I still have the factory sticker to prove it and no it wasn't a dealer add on.

camperforlife - You're correct about GM offering 20's in 2003. I actually used that fact to argue with my dealer about why they couldn't use the 20's argument to void my warranty.

But N-Trouble is right that it's more likely an issue caused by cranking the torsion bars to raise the front end, and not the 20's themselves.

You can run 20's with lower profile tires and have the same overall size as 18's; it's when you run 20's with larger tires, and then you have to crank the Torsion Bars to get more clearance. That's when the ride suffers.

I understand what both of you are saying about cranking the torsion bars but that would have been done at the factory to accomadate the 20's therefore the suspension should have been tuned for the 20's. I know it wasn't done if it wasn't done at the factory.

I also realize that 20's are far more popular than in 03 and I'm sure the tweaks in the suspension the manufacturers have done to accommodate the 20's has to have come a long way from what I had and comparing mine to the OP's probably isn't fair. I know when it was time for me to replace my 20's I had 2 choices, 1 Goodyear and 1 Michelin and I had tire dealers argue that the 20's weren't factory. I ended up buying tires at a GMC dealer at a better price anyway.
dodge_guy
Explorer II
Apr 28, 2015
Stick with the 18's and go with a taller tire! This will give you more sidewall flex when aired down off road. You will need to reprogram the computer with the larger tire size.
Slowmover
Explorer
Apr 28, 2015
Spend the money where it matters. A Pro Pride hitch and TUSON sourced antilock trailer disc brakes.

There are more choices of tires in 18". That may matter at some point. I would not want the short sidewall 20's.

And be sure to spend time over on www.airforums.com for about a half million posts on Airstream trailers.
MPond
Explorer
Apr 28, 2015
camperforlife wrote:
N-Trouble wrote:
camperforlife wrote:
Nice truck. My 03 Sierra had factory 20's. Loved the looks, hated the handling. My 11 Sierra has the 18's and I'll never go back to the 20's regardless of good they look.

GM never made 20's in 03... Doubt it was due to the wheels.******ride on the 03 was more likely due to over cranking the T-bars and overextending the shocks. Very common mistake amongst GM owners. With the right tire your not going to feel much of a difference in ride between 18" and 20" rims.

You and the tire dealers thought the same thing. I've argued before to the nay sayers that GM offered 20's in '03. I bought it new, it was factory and I still have the factory sticker to prove it and no it wasn't a dealer add on.

camperforlife - You're correct about GM offering 20's in 2003. I actually used that fact to argue with my dealer about why they couldn't use the 20's argument to void my warranty.

But N-Trouble is right that it's more likely an issue caused by cranking the torsion bars to raise the front end, and not the 20's themselves.

You can run 20's with lower profile tires and have the same overall size as 18's; it's when you run 20's with larger tires, and then you have to crank the Torsion Bars to get more clearance. That's when the ride suffers.
camperforlife
Explorer
Apr 28, 2015
N-Trouble wrote:
camperforlife wrote:
Nice truck. My 03 Sierra had factory 20's. Loved the looks, hated the handling. My 11 Sierra has the 18's and I'll never go back to the 20's regardless of good they look.

GM never made 20's in 03... Doubt it was due to the wheels.******ride on the 03 was more likely due to over cranking the T-bars and overextending the shocks. Very common mistake amongst GM owners. With the right tire your not going to feel much of a difference in ride between 18" and 20" rims.

You and the tire dealers thought the same thing. I've argued before to the nay sayers that GM offered 20's in '03. I bought it new, it was factory and I still have the factory sticker to prove it and no it wasn't a dealer add on.
N-Trouble
Explorer
Apr 24, 2015
camperforlife wrote:
Nice truck. My 03 Sierra had factory 20's. Loved the looks, hated the handling. My 11 Sierra has the 18's and I'll never go back to the 20's regardless of good they look.

GM never made 20's in 03... Doubt it was due to the wheels.******ride on the 03 was more likely due to over cranking the T-bars and overextending the shocks. Very common mistake amongst GM owners. With the right tire your not going to feel much of a difference in ride between 18" and 20" rims.
APT
Explorer
Apr 23, 2015
Choose the wheels you want based on looks. If you got the money, I don't care how you spend it. Most OEM wheel/tire combinations provide the same overall diameter, so no computer adjustments are necessary. Now if you if want larger tires, like 33-35" vs. OEM 32", then you should consider the effects of more rotational/unsprung weight. For that a modern diesel truck towing an Airstream, I doubt the effects will be noticeable compared to a gasser.

I strongly discourage a front lift kit only. The higher in rear unhitched rake is designed to support the 2200-ish pounds of payload that mostly goes in the truck bed. If you never loaded the truck, go for it. Since you plan to use it like a truck, don't change the stance.