2020 GMC SIERRA AT4 with Readylift 2" SST

Supercup · May 9, 2020

3 hours ago, Roy Hutchinson said:

However, this truck with its suspension upgrades and tire/wheel combination, rides extremely softer/smoother than my recent 2017 GMC Sierra Denali with leveled suspension and 33 inch Toyos and 22 inch stock wheels. Not sure if it's because of the Rancho coil/overs or what but my 2020 is night and day as compared to my previous Denali.

Glad to hear it, the truck I drove was a 4WD GMC Sierra (dealer loaner) with Rancho shocks and 22's like yours. I was suprised at how poorly it road in comparison to my AT4. The Rancho shocks the TB and AT4 have are not the same as the Z/71. The TB/AT4 have monotube Ranchos's vs the Z/71 having twin tube Ranchos. You can read more about differences on the link below:

Link: https://www.strutmasters.com/the-difference-between-twin-tube-and-monotube-shocks/

Enjoy your ride!

Josh021 · January 27, 2023

Just added this kit I have no issues in 4wd auto 4wd hi or low and 2wd. Truck works like a charm. The picture of the cv the guy showed st the top must not have been properly installed. My cv looks nothing like that. But I also don't shift on the fly anymore so that's probably where the issue is. Running 275/65r20 right now. Adding 285/65r20 bfg ko2 next week with a 2 inch spacer. Also removing the side steps and ordering rock sliders. The cv is angeled up because I'm parked on a bump in my drive on flat they're perfectly straight.

Edited January 27, 2023 by Josh021

2021 At4 1500 · April 18, 2025

On 5/6/2020 at 3:06 PM, Supercup said:

I have the same lift - I stayed with 275/65/18 Duratrak wranglers that came on truck - but swapped out wheels to Method.

Be aware that Ready Lift does not recommend you use auto 4WD with this level kit - from website "NOTE: Use of Auto 4 HI feature not recommended" - due to having customers who have damaged their front diff using it.

they say you can fit "AT4 - Max tire 305/55-20, 20x9 0 offset wheelTrail Boss - Max tire 295/65-20, 20x9 0 offset wheel"

As you can see they make no statements for 18" wheels - here are some photos of clearance to my upper control arm - about a finger width - so you can't go much wider than 275, without getting a spacer or wheels with different offset than stock.

Note in my last photo the angle of cv axel - not ideal.

Do a search on AT4 and TB and there a lot of threads on this topic and many have gone larger - but the wheel well is tight and the spacing as well to the upper control arm.