Tire size!

ahartzell2020 · April 5, 2021

I’m getting a 3” RC lift/level and vertex shocks installed on my 2020 duramax. I want to keep the stock AT4 wheels. I’m getting lots of conflicting info from what I can run without rubbing or trimming. I’ve seen people running 35x12.5x20 stock but lift guy is saying he’d still go with 35x11.5x20 to prevent rubbing. But I’ve also seen people running 37x11.5x20 on leveled trucks.

Bottom line is I want a “stuffed” look similar to the posted pic and I don’t want rubbing at all. Does anyone have a similar lift and tire combo that could share experience?

*pic not my truck. According to caption it’s “leveled with 37s”* but this is the look I’m going for. Don’t like the tires sticking outside fenders and I don’t want them looking too small for the truck after it’s lifted.

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CT Chevy Connoisseur · April 6, 2021

Depends on rims and offset - I went from 18x9 with 275's stock to 20x10 with 35's. Equivalent lift as yours due to offset minor trimming was required to inside of mudflaps, rubbed at full turn. Nothing major though, easy trim.

ahartzell2020 · April 6, 2021

Depends on rims and offset - I went from 18x9 with 275's stock to 20x10 with 35's. Equivalent lift as yours due to offset minor trimming was required to inside of mudflaps, rubbed at full turn. Nothing major though, easy trim.

Plan A: use stock AT4 rims
Plan B: Fuel Rebel 20x9 +1 offset

Plan C: get 5” zone lift with fox shocks and then plan A or B [emoji23]

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Cmuff · April 7, 2021

I am looking to put 35's on 2021 AT4 HD and was initially going to order a Cognito kit but lately I am undecided. I personally think with the 3" lift it needs 37's to fill up the wheel well. I have seen a couple of forums where people have put 35's on and gone up 1/2" or so with adjusting their torsion bar keys. I am just not sure how hard on the ball joints, etc. that 1/2" of adjustment would be without the longer control arms... Looking forward to some more comments on this thread on it. Cheers.

ahartzell2020 · April 7, 2021

I am looking to put 35's on 2021 AT4 HD and was initially going to order a Cognito kit but lately I am undecided. I personally think with the 3" lift it needs 37's to fill up the wheel well. I have seen a couple of forums where people have put 35's on and gone up 1/2" or so with adjusting their torsion bar keys. I am just not sure how hard on the ball joints, etc. that 1/2" of adjustment would be without the longer control arms... Looking forward to some more comments on this thread on it. Cheers.

Well I’ll let you know next week! I called a bunch of places (because everything including lifts and tires are on back order) and I finally found a really reputable shop that had the cognito 3” elite leveling kit and tires in stock. Going to try both 35s and 37s to see what fits without rubbing and what looks best.

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CobraEatr · April 7, 2021

5 hours ago, ahartzell2020 said:

Well I’ll let you know next week! I called a bunch of places (because everything including lifts and tires are on back order) and I finally found a really reputable shop that had the cognito 3” elite leveling kit and tires in stock. Going to try both 35s and 37s to see what fits without rubbing and what looks best.

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Yes, please let us know how it goes. I’m in the exact same situation that you are in. I too want the “stuffed” look and am going to run the 37s. My current plan is to go with the Cognito premier leveling kit, use my stock 20” wheels, and install either 37x11.50 or 37x12.50 Nitto Ridge or Trail Grapplers. Nitto is the only company to make a 37x11.50x20. I want the thinner tire but am worried that the tires will look too skinny. The 11.50 tires are lighter and have less rubber contacting the road, so I know the mpg won’t suffer as much as the 12.50 tires.

I am going to assume that the shop you found with the tires in stock are 37x12.50x20 since the 11.50s are very rare. I can’t find many pics of the 37x11.50 on a leveled 2500hd.

Please take a lot of pics (both side, front on, and rear) and let us know how it goes. Good luck!

ahartzell2020 · April 7, 2021

Yes, please let us know how it goes. I’m in the exact same situation that you are in. I too want the “stuffed” look and am going to run the 37s. My current plan is to go with the Cognito premier leveling kit, use my stock 20” wheels, and install either 37x11.50 or 37x12.50 Nitto Ridge or Trail Grapplers. Nitto is the only company to make a 37x11.50x20. I want the thinner tire but am worried that the tires will look too skinny. The 11.50 tires are lighter and have less rubber contacting the road, so I know the mpg won’t suffer as much as the 12.50 tires.

I am going to assume that the shop you found with the tires in stock are 37x12.50x20 since the 11.50s are very rare. I can’t find many pics of the 37x11.50 on a leveled 2500hd.

Please take a lot of pics (both side, front on, and rear) and let us know how it goes. Good luck!

Will do! Running into some issues already.

Per Cognito: the leveling kits allow max of 12” tire on stock rim (so only XXx11.50) or you have to get a 9” wide wheel with 0 offset to fit XXx12.50.

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CobraEatr · April 7, 2021

8 minutes ago, ahartzell2020 said:

Will do! Running into some issues already.

Per Cognito: the leveling kits allow max of 12” tire on stock rim (so only XXx11.50) or you have to get a 9” wide wheel with 0 offset to fit XXx12.50.

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The 37x12.50x20 tires will definitely fit on the stock wheels with a leveling kit. I found two posters on here that did it and it looks great. It does rub a bit at full lock (both posters say so), and that’s why I considered the 11.50. The one posters name is gswift. Look him up and you can see his pics. His truck looks amazing. He went with the 37x12.50x20 Ridge Grapplers.

ahartzell2020 · April 7, 2021

The 37x12.50x20 tires will definitely fit on the stock wheels with a leveling kit. I found two posters on here that did it and it looks great. It does rub a bit at full lock (both posters say so), and that’s why I considered the 11.50. The one posters name is gswift. Look him up and you can see his pics. His truck looks amazing. He went with the 37x12.50x20 Ridge Grapplers.

Just talked to the shop again. I’m going to put on 20x9 fuel rebels or coverts and 37x12.50x20 nitto ridge grapplers. Don’t want to do spacer or a thinner tire (unless 37x11.50 looks ok).

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CobraEatr · April 7, 2021

29 minutes ago, ahartzell2020 said:

Just talked to the shop again. I’m going to put on 20x9 fuel rebels or coverts and 37x12.50x20 nitto ridge grapplers. Don’t want to do spacer or a thinner tire (unless 37x11.50 looks ok).

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Well piss! Lost another one to the dark side. I need more info from the stock wheel guys. I have yet to see an aftermarket wheel that I like better than the stock wheels, and wheels that stick out past the fenders look ridiculous to me - but that’s because I’m old (42). Good luck to you either way.

Edited April 7, 2021 by CobraEatr

ahartzell2020 · April 8, 2021

Well piss! Lost another one to the dark side. I need more info from the stock wheel guys. I have yet to see an aftermarket wheel that I like better than the stock wheels, and wheels that stick out past the fenders look ridiculous to me - but that’s because I’m old (42). Good luck to you either way.

Yep! I’m with you. I was VERY picky so I got lucky the shop had them in stock. And I made sure the offset would work with lift and also was as tucked in as possible.

My options came down to:
(1) stock rims and 11.50 wide tire
(2) stock rims, 12.50 wide tire, and large spacer
(3) new rims, 12.50 wide tire

I wanted 12.50 wide and didn’t want spacer so the decision was pretty much made for me.

After all is said and done, it will be the Cognito 3” elite level with 2.5 fox resi shocks, 20x9 Fuel Covert in matte black with 37x12.50 ridge grapplers.

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CobraEatr · April 8, 2021

Awesome! Please post pics (front, back, and sides) when you are done. That's going to look really nice.

gSwift · April 9, 2021

Here is my truck. 3" Cognito Premier leveling kit with 37 12.50's and stock wheels. Had minor trimming on the liners and the mud flaps. The biggest issue is the stock wheels will make contact with the Cognito upper control arms at full lock, so I had to add a 1" wheel spacer and then everything was perfect. I was never a fan of spacers, but as long as its not too big its not bad, the biggest thing is getting a quality spacer that is hubcentric. I had absolutely ZERO vibrations at any speed range

Not sure if the stock wheels would contact the control arms on the RC lift or not. I was told by Cognito that I couldn't run 37's on stock wheels with their kit, but I chose to buy what I wanted and make it work. That may be what you need to do as well.

Edited April 9, 2021 by gSwift

ahartzell2020 · April 18, 2021

Here are some after pics

Minimal trimming, no rubbing at full lock but it is within finger width of soft liner near front bumper.

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Simsy · April 18, 2021

Not directly answering your question but I put the metric equivalent of a 35/11.50r20 they are 295/65R20 on without lift or level and don’t rub one bit