Tow truck 18” tires to 20” tires

[NB Canada]

Bigger rims = less rubber (sidewall) between you and the road = Harsher ride. The lower the tire profile (height) the less cushion there is.

That said, as others have commented, the overall height should be the same, or darn close. But 20's will ride harder and be more expensive to replace. Also, look at the load ratings available in your size, you may have fewer options for high weight rated tires in larger rim sizes.

There isn’t any other option on the truck for tires

That is standard

[JFF&KRN]

I went form a 2010 sierra with 16 inch tires and wheels to a 2019 silverado with 20inch. same trailer, no issues with adjustment on the hitch etc. all fine, bed clearance etc was fine. Biggest issue for me was the less sidewall rubber when not towing i don't have the little bit of extra cushion and when out be bopping around in the hills when in four wheel driev, ( not that i am doing anything crazy) I just like the softer ride and can lower air pressure for sand and snow if i want or need to. Just me and my opinion iclude my by OCD. Besides you will use more soap to clean as there is a bit more wheel!!!

[chillybob]

Well, here’s the scoop on my posting. I bought the new 2023 3500 Denali, so far it’s great. Unknown to me, GM changed the spacing of the hitch anchor system in 2020. Narrowing the spacing by about 5 inches. So I had to upgrade my Q20 Curt hitch by buying new legs. I didn’t measure the difference but the new looks higher than it was in my 2018 Denali. I hooked up to my fifth wheel to see how much clearance and it’s around 5 inches. I’ll have to wait until I get the unit on flat ground to better assess how level it is hooked up. The bottom line is that it looks like I don’t have to do any more modifying. Moral of the story is to check your hitch to see if it will work in a new truck so you won’t be surprised.

[avidcamper]

Like someone said the bed was changed in 2020 to a longer version but I think the rails are a little lower. The overall truck stands a little taller. As for the wheels, no difference in height from 18" to 20". Now I feel the 20's are better for towing having a shorter sidewall results in less squish. Not that LT tires have weak sidewalls. There is plenty of sidewall there and if you somehow damage a rim, you hit a deep pothole or curb at excessive speed. I went from a 2016 GMC 2500 to a 2021 GMC 3500. I use an Anderson hitch and had to drop the top of hitch ball one hole and still have 7" of clearance to top of bed rail. Trailer sits level. The longer bed gives me more turning radius till the cab/trailer contact.

[chillybob]

Like someone said the bed was changed in 2020 to a longer version but I think the rails are a little lower. The overall truck stands a little taller. As for the wheels, no difference in height from 18" to 20". Now I feel the 20's are better for towing having a shorter sidewall results in less squish. Not that LT tires have weak sidewalls. There is plenty of sidewall there and if you somehow damage a rim, you hit a deep pothole or curb at excessive speed. I went from a 2016 GMC 2500 to a 2021 GMC 3500. I use an Anderson hitch and had to drop the top of hitch ball one hole and still have 7" of clearance to top of bed rail. Trailer sits level. The longer bed gives me more turning radius till the cab/trailer contact.

Thanks Avidcamper
As you can see from my follow-up post, everything turned out well in the end. I had to upgrade my Q20 Curt hitch which made the hitch a little higher than the old version and the extra height helped. The box is 1/2” deeper than the ‘18 and the holes for the hitch legs about 5” more narrow. It’s now fixed and works for my next tow.

[WhittleBurner]

Like someone said the bed was changed in 2020 to a longer version but I think the rails are a little lower. The overall truck stands a little taller. As for the wheels, no difference in height from 18" to 20". Now I feel the 20's are better for towing having a shorter sidewall results in less squish. Not that LT tires have weak sidewalls. There is plenty of sidewall there and if you somehow damage a rim, you hit a deep pothole or curb at excessive speed. I went from a 2016 GMC 2500 to a 2021 GMC 3500. I use an Anderson hitch and had to drop the top of hitch ball one hole and still have 7" of clearance to top of bed rail. Trailer sits level. The longer bed gives me more turning radius till the cab/trailer contact.

I measured our 2022 GMC at the tailgate and it was 58 and a half inches. On a old post I believe it was on a 2025 it was 54 inches. That would explain my having to adjust the hitch and pin box to stay level.