2021 AT4 - Stock Wheels, Biggest Tire W/Out Rubbing

[RichieBee]

Just had mine leveled 2” with 285/70R18 Nitto Ridge Grapplers. (33.98 x 11.5, according to Nitto’s  website)

[JT2000]

16 hours ago, RichieBee said:

Just had mine leveled 2” with 285/70R18 Nitto Ridge Grapplers. (33.98 x 11.5, according to Nitto’s  website)

Looks good. So what level did you do?

[Hulkmanj99]

On 7/26/2021 at 1:30 PM, MC AT4 said:

Wanted to post my research and share my decision on selecting larger tires on a Factory '21 AT4, 20" Wheels. 

 

There are a lot of threads on this topic, all with great content, but there are some conflicting posts on size choice/rubbing/mpg impact that can make the decision difficult. As others have noted not all tires measure the same height/width/weight, so a one-size fits all approach likely cannot be taken. 

 

**In case you don't want to read through all the details below, I went with BFG KO2 in a 275/65R20. No rubbing, plenty of UCA clearance, ~1MPG loss, speedometer is off between .5 to 1MPG depending on speed. ~1MPG loss does not reflect accounting for speedo variances. I will need to update this post with a manual calculation. I do think you could fit a slightly larger tire, depending on manufacturer choice (see below variations of sizing). 

 

Tire Size:

Based on reading through other posts I narrowed my tire size to three options: 

1. 275/65R20

2. 285/65R20

3. 295/60R20

 

I personally didn't want rubbing issues after tire install. Minor trimming (IE: mud flap trimming) wouldn't be a big deal, but having owned a truck that had rubbing issues, it gets old quick and I wanted to avoid modifications if possible. 

 

Pros/Cons of each tire size I contemplated:

• 275/65 - great tire size as you get 34" in height, but can appear to have a narrow stance depending on tire choice. Stock tire (Bridgestone Dueler A/T 275/60/20), width would remain the same as stock. Originally ranked 2nd of the 3 options. 
• 285/65 - best of both worlds, gains in height and width. Ranked 1st of 3 options. Big concern around rubbing issues, especially at full lock on an incline. Likely could avoid by adding a levelling kit. Conflicting results on CV angles and longer-term impact of adding a level kit. 
• 295/60 - prefer the stance of a 295, but didn't have a high level of confidence there would be clearance from the UCA. Rubbing concerns similar to 285/65. 

 

Tire Brand:

1. Falken Wildpeak AT3W

• 275/65 - 34.1" X 10.6", 66.1lbs
• 285/65 - 34.6" X 11.2", 67.7lbs
• 295/60 - 33.9" X 11.6", 69.4lbs

2. Toyo AT3

• 275/65 - 34.1" X 11", 54lbs
• 285/65 - Not Offered
• 295/60 - 33.9" X 11.8", 60lbs

3. BFG KO2 

• 275/65 - 34" X 11", 57.3lbs
• 285/65 - 34.5" X 11.5", 60.3lbs
• 295/60 - 33.9" X 11.8", 68lbs

**4. After decision came across Mickey Thompson Baja Boss A/T (some great reviews coming out on this tire). 

 

Pros/Cons of each tire size I contemplated:

• Falken - awesome tire with some fantastic reviews. Major consideration was the weight.
  • Example: 275/65/20 weighs 66.1lbs 
    • Toyo AT3 = 54lbs
    • BFG KO2 =  57.3lbs
• Toyo AT3 - I've had several sets of Toyo AT2's. Really like the upgrades made to the AT3, but wanted a slightly more aggressive sideway. I also found it very difficult to find inventory at the moment. 
• BFG KO2 - tried and true, some question around if newer technology is surpassing. Obviously not enough of a concern as this was the tire of choice. 

 

 

 

 

First off... THANK YOU for this great post. I just bought my 21' AT4 with 20s and have been conflicted with so many posts. I actually signed up for this forum just to thank you!

 

I have been on many forums over the years, but none with GM Trucks, so this was great. You definitely helped me narrow down to 2 tires (275 & 285 65s). This is the type of post I love to see and you deserve kudos for it. Informative, definitive and well written.

 

Your truck looks awesome and I appreciate you!

 

-Jamo

[Hulkmanj99]

Edit: so excited i posted 3 times

Edited August 12, 2021 by Hulkmanj99
Duplicate post

[Hulkmanj99]

Thanks to all you who reply and help out! love to see it!

Edited August 12, 2021 by Hulkmanj99
duplicate post

[grebner1]

Hi all! I thought I’d post my findings in an effort to help people with their decisions.

 

2020 AT4, Readylift SST, 20x9 Fuel “Crush” wheels with +1 offset, 275/65R20 FALKEN WILDPEAK A/T3W tires.

 

I had a little rubbing. Very, manageable and mitigated the issue by trimming the plastic only. You genuinely cannot tell where I trimmed whatsoever, and took my time with a utility knife and a little sandpaper. 

 

Below the bumper are two plastic spoilers. The outermost ends of where these two spoilers bolt together, is the issue. It’s very obvious, and quite honestly, a poor design on GM’s part. Believe it or not, by trimming off these two connection points, the wheel wells look cleaner, and better than factory. Structural integrity is not compromised in any way, shape or form, and no metal has to be touched. I am more than happy to post pictures is there is an interest.

[JEP]

What about the speedometer and adjusting for the larger tire size?  Is there a programer yet for the 2023 3.0L Duramax?

[Transient]

On 12/10/2023 at 8:54 PM, JEP said:

What about the speedometer and adjusting for the larger tire size?  Is there a programer yet for the 2023 3.0L Duramax?

I believe your 2 options are Rough Country at about $250 and Pulsar LT at $600+