Tow truck 18” tires to 20” tires

[WhittleBurner]

You'll likely have to do a little adjusting on both the hitch and pinbox. I don't recall what Gary had to do but when we went from our 2015 to the 2022 there is a noticable difference in height and width of the 2 trucks. He'll likely chime in with what combo he changed

[Tom Traveler]

Has anyone had experience going to 20” tires from 18”? I have a 2018 Denali with 18” tires and now going to a 2023 Denali with 20” tires. I have a 2018 Reflection 329 which is very similar to the 337 models. I’m not sure if I’ll have to lower the pin box to raise the trailer a couple of inches to clear the box rails adequately. Thanks for any info.

I seem to be having a case of deja vu here. I don't see how different size wheels/tires on the truck changes the distance between the RV and the truck box rails. If you are using the same hitch and the distance between the truck bed and bed rails is the same, the distance between the RV and the bed rails will be the same. The size of the truck's wheels/tires is irrelevant here. There might be a very small change in the angle of the RV with respect to the truck. If the radius of the tire is 1" greater, (+2" in tire diameter) and nothing is done to the trailer, the tailgate will be about 3/16" closer to the bottom of the RV for an 8 ft bed, less for a short bed - this is negligible. The angle of the RV will change by about 0.25° - again negligible. The only impact will be a 1" rise in the overall height of the front of RV.

[traveldawg]

Has anyone had experience going to 20” tires from 18”? I have a 2018 Denali with 18” tires and now going to a 2023 Denali with 20” tires. I have a 2018 Reflection 329 which is very similar to the 337 models. I’m not sure if I’ll have to lower the pin box to raise the trailer a couple of inches to clear the box rails adequately. Thanks for any info.

Since you are changing trucks I don't think it is a question of the size of the tires. It's a question of the height of the bed rails compared to each other.

As far as 18" vs. 20" - if it was a 2022 Ford the bed hight would be the same; the profile of the different size tires keeps the hight pretty much constant.

fwiw.... here is a comparison of the 2018 to the 2022 GMC 2500 Denali..... looks you will be 2" taller (oh - I noticed that whether it has 17", 18" or 20" tires the heights are the same - again the profile of the tires keeps the height pretty much the same)

2018:


2022:

[chillybob]

Good point, the tailgate may be tight to the trailer overhang when going into a dip with the front wheels of the truck. I’ll be able to do some measuring for comparison tomorrow. Thank you.

[traveldawg]

Good point, the tailgate may be tight to the trailer overhang when going into a dip with the front wheels of the truck. I’ll be able to do some measuring for comparison tomorrow. Thank you.

For sure you will want to get the RV a good 4" or more above the tailgate to avoid any interference. I use to have just under 4" and have the RV scares to prove it. It's always when you dip and turn that gets it.

[WhittleBurner]

Going from our 2015 Denali to our 2022 Denali I had to raise our hitch to the top of it's setting and our pin box to it's lowest setting. That left us 3/4 of an inch off of being level.

[Wileykid]

The bed of the Chevy changed in 2020. It went from a 6'6" to a 6'10" size, not sure if the bed rail is taller, or shorter, but they did move the pucks further back several inches in the bed. The hitch manufacturers changed the leg height of the hitches for the trucks, 2020 and after.

I switch from a RAM to a '23 Chevy 3500, and ordered new legs for my hitch, which is 2-6 weeks on back order.

[johndeerefarmer]

For Ford's the overall height of the tires are the same. The problem with 20's is you get less rubber which means it's easier to bend a rim. I will not buy a truck with 20's for towing. On top of that 20's cost more..

[chillybob]

Going from our 2015 Denali to our 2022 Denali I had to raise our hitch to the top of it's setting and our pin box to it's lowest setting. That left us 3/4 of an inch off of being level.

Thanks Wittleburner
It looks like I should be prepared to move the pin box to raise the trailer. It’s the only option that I have.

[Overtaxed]

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.