Are Spare Tires the Same for 2020 1500 AT4 and 2022 1500 Denali?

MrLeadFoot · February 11, 2023

1 hour ago, swathdiver said:

Ok, I get it, I don't think it's the tires or wheels then. Could it be an out of round hub or axle shaft? Maybe. More than likely is that the suspension needs to be re-calibrated. It's a Z95 Magneride right? I read a few times that the last generation would often need re-calibrating to stay in tune. This can only be done with the dealer level bi-directional scan tool or a Snap-On scanner.

The jostling over bumps and train tracks, especially when you feel it up front in the steering wheel is how the alignment is set. I think you need more caster.

https://autoquarterly.com/wheel-alignment-what-is-caster/

Reduced Sensitivity to Road Conditions

It might seem like a bad thing to have to turn the steering wheel more to get the car to turn, but the truth is that it’s actually a lot more comfortable. Roads are not perfectly smooth. They have a lot of bumps and imperfections, and each imperfection knocks the wheel around. If the steering input was very sensitive, that would translate directly to your wrists and jerk the steering wheel around.

Instead, with a positive caster, the steering system can absorb all those road imperfections without moving the car around. On a long stretch of highway, that means you don’t have to make constant corrections to stay on the road.

I like where you're going with this, but I don't feel the steering wheel jerking around over bumps, I feel the shaking in the body of the truck itself. I do, however, feel that I'm always adjusting to keep the truck straight on the freeway.

Fwiw, it's not magnetic shock fluid anymore. They went back to electronically adjusted valving instead. It is entirely possible, in my mind, that the shocks are adjusting improperly over bumps, whether big or small, and the vibration felt on the freeway is because road imperfections are smaller on freeways, so the shocks could be constantly adjusting, and making it feel like a tire vibration, and on city street bumps you feel it more because the bumps are bigger. I'm wondering if the shocks are reacting too slowly.

Swapping tires and wheels is simply an exercise to potentially eliminate the issue being tires and wheels, because that's where the dealer is looking right now, and the only way to eliminate wheels/tires is to try completely different wheels.

Edited February 11, 2023 by MrLeadFoot

swathdiver · February 11, 2023

Hmm, well I did some poking around in my AllDataDIY subscription, the shop manual for my truck and came across to diagnostic resets that are done with the dealer level scan tool usually when suspension components are replaced on Z55 or Z95 equipped trucks.

One is called ALC, Automatic Level Control Trimset Procedure and the other Bumpstop Setup.

On our older trucks, we use Tech-2s and the guys on the TahoeYukon forum used them when they replaced parts of their Z55 suspension and were talking back and forth about the percentage that the dampner actuators moved while they were driving.

Well, something to keep in mind once you eliminate the tires.

My trucks all have dumb suspensions so I can't see any of that stuff. Keep us posted if you will.

MrLeadFoot · February 11, 2023

I took the 240 lbs. of sand out of the truck a couple of days ago, since it didn't help. This morning, I decided to take the sand back to the store. Instead of putting it up against the cab, I just placed it right at the tailgate to make it easier to unload at the store. On the way back to the store, I notice a significant difference in the ride. The vibration that feels like out of balance tires is still there but the ride over bumps is smoother. There is still some judder, but less of it, too. Because the vibration of the freeway did not change, this really makes me think the wheels/tires are an issue, or part of the issue. Even though there is MUCH more sidewall on these 22" wheels than my Vette that has 40s on the back and 45's in the front (and doesn't have road vibration issues), I'm wondering if it's possible that the wheels/tires on the truck are transmitting much more road feel into the truck because the truck is heavier than my Vette. Is it possible that the judder I feel over bumps is actually an exaggeration of the vibration issue in these wheels/tires, and if the wheels/tires did not vibrate, then the judder would be gone, too?

Instead of returning the sand, I decided to keep it a little longer, so I can drive around for a few more days to see if I notice anything other difference that might help "steer" the dealership into a resolution. I want to also try NOT to look for anything, but because I've been consumed by this for so long, that will be hard to do. As you can tell, I'm reaching here, but I think anyone would be reaching if they'd have been dealing with this issue as long as I have. So, thanks for bearing with me, and offering suggestions and feedback.

Edited February 11, 2023 by MrLeadFoot

MrLeadFoot · March 5, 2023

Was scheduled to go in for a Pico scope, but had to reschedule due to weather.

In the meantime, swapped wheels with a friend who has a 2020 Silverado LTZ with stock 20" wheels.

Drove his truck first, and I gotta say that while the Denali shocks are way better over dips and rises, over bumps and on freeway his truck rode MUCH better.

Then we swapped wheels. Even with 29000 miles on his stock AT tires, my truck drove WAY nicer with his wheels on it than my brand new Denali with 22" tires and wheels ever did. And, no tire vibration any more.

That said, I still feel a little vibration/shaking in the cab. I always thought I had more than one issue. Pico scope due to be performed on Tuesday, but I don't think they're gonna be able to fix this. They would have to swap wheels with 20" to get the tire vibration out of the way so they can detect the other vibration, but I bet they don't go to the "trouble" of doing so. All I can do is share with them what I found, and pray they really care enough to go to those lengths.

On another note, turns out the 20" wheel/tire diameter is larger than the 22", so if they do offer to give me 20" setups as a partial fix, would the spare need to be replaced as well, or would it be ok to have a slightly smaller spare?

Edited March 5, 2023 by MrLeadFoot

newdude · March 6, 2023

On 3/5/2023 at 6:39 AM, MrLeadFoot said:

Was scheduled to go in for a Pico scope, but had to reschedule due to weather.

In the meantime, swapped wheels with a friend who has a 2020 Silverado LTZ with stock 20" wheels.

Drove his truck first, and I gotta say that while the Denali shocks are way better over dips and rises, over bumps and on freeway his truck rode MUCH better.

Then we swapped wheels. Even with 29000 miles on his stock AT tires, my truck drove WAY nicer with his wheels on it than my brand new Denali with 22" tires and wheels ever did. And, no tire vibration any more.

That said, I still feel a little vibration/shaking in the cab. I always thought I had more than one issue. Pico scope due to be performed on Tuesday, but I don't think they're gonna be able to fix this. They would have to swap wheels with 20" to get the tire vibration out of the way so they can detect the other vibration, but I bet they don't go to the "trouble" of doing so. All I can do is share with them what I found, and pray they really care enough to go to those lengths.

On another note, turns out the 20" wheel/tire diameter is larger than the 22", so if they do offer to give me 20" setups as a partial fix, would the spare need to be replaced as well, or would it be ok to have a slightly smaller spare?

The 20s and 22s use the same size spare 255/80R17. Stock 22 size is 275/50R22 which is 32.8", 20s are 275/60R20 which is 33" so .2" is a negligible difference.

MrLeadFoot · March 14, 2023

GM is basically screwing me (and others with the same issue, as I've recently discovered). Pico scope showed vibrations, but bottom line is Field Engineer that came out for the test said they are not doing any more to try to resolve this and are blaming it on stock 22" wheel/tire setup, even though I told them one of the vibrations was still there after trying out my friend's 20" wheels. They did not bother trying different wheels size like I did, nor did they have a similar vehicle on the lot to compare Pico readings with. The factory rep could easily have gone literally across the street to another GM DEALERSHIP that did have a similarly-equipped truck right on the front line. Ironically GM Case Adivisor has suddenly stopped following up, too.

Now, it is possible that while my friend's 20" wheels served to mitigate road vibrations, his tires do have 29,000 miles on them, and maybe they have a little "wear" vibration that is 9nly able to be felt omy truck {didn't feel it when I drove his), so I'm willing to take yet ANOTHER gamble with this truck, and try different wheels/tires before I pursue a lemon law case with an attorney I have already been in talks with. I haven't slept in months since throwing away $80k on the truck, and I need to know once and for all if this really is a simple wheel issue, which I apparently have to figure out myself, just so I can start getting some sleep. I need to be able to at least drive the truck, even if I do proceed with a lemon law resolution, and if wheels and tires resolve the issue, I'll drop the case.

That said, according to what I'm finding, 275/50/22 is 32.9" (not 32.8"), while 275/60/20 is 33", which makes the difference even more negligible.

If the 20s with AT Duehlers rode that much better, and were not at all noisy even if 29000 miles on them, wouldn't it stand to reason that 18s would be even better with more sidewall? What if I went with 18" AT4 rims and upped the tire to 285/65/18 so I'd have a 32.56" diameter instead of the stock 32.1"? Is that too much spread between that and my stock 32.9" diameter? And, if my diameter really is 32.8" like you said, and a .2" difference is negligible, then it's the same difference either way to go 20s or 18s. One caveat here is that the only tire in that size in the SL load range is the Falken Wildpeak AT3/W. Other considerations are:

1) Will a 285/65/18 even fit in my stock-height wheel well?

2) Am I asking for trouble in the future if only one tire fits my criteria now? (all others are e rated and I'm after comfort)

3) Are those Falken any good for street, or will their tread be too noisy, and slippery when wet?

4) No one else on here with a Denali seems to run 18s. Is there a reason for that, that I'm missing something here, and I should stick to only considering 20s?

Thanks for any additional thoughts.

Edited March 14, 2023 by MrLeadFoot

Homewrecker007 · March 14, 2023

39 minutes ago, MrLeadFoot said:

GM is basically screwing me (and others with the same problem I'm now seeing). Pico scope showed vibrations, but bottom line is Field Engineer that came out for the test said they are not doing any more to try to resolve this and are blaming it on stock 22" wheel/tire setup, even though I told them one of the vibrations was still there after trying out my friend's 20" wheels. They did not bother trying different wheels size like I did, nor did they have a similar vehicle on the lot to compare Pico readings with. The factory rep could easily have gone literally across the street to another GM DEALERSHIP that did have a similarly-equipped truck right on the front line. Ironically GM Case Adivisor has suddenly stopped following up, too.

Now, it is possible that while my friend's 20" served to mitigate road vibrations, his tires do have 29,000 miles on them, and maybe they have a little "wear" vibration that is 9nly able to be felt omy truck {didn't feel it when I drove his), so I'm willing to take yet ANOTHER gamble with this truck, and try different wheels/tires while I pursue a lemon law case. I need to be able to at least drive the truck in the meantime, and if wheels and tires resolve the issue, I'll drop the case.

That said, according to what I'm finding, 275/50/22 is 32.9" (not 32.8"), while 275/60/20 is 33", which makes the difference even more negligible.

If the 20s with AT Duehlers rode that much better, and were not at all noisy even if 29000 miles on them, wouldn't it stand to reason that 18s would be even better with more sidewall? What if I went with 18" AT4 rims and upped the tire to 285/65/18 so I'd have a 32.56" diameter instead of the stock 32.1"? Is that too much spread between that and my stock 32.9" diameter? And, if my diameter really is 32.8" like you said, and a .2" difference is negligible, then it's the same difference either way to go 20s or 18s. One caveat here is that the only tire in that size in the SL load range is the Falken Wildpeak AT3/W. Other considerations are:

1) Will a 285/65/18 even fit in my stock-height wheel well?

2) Am I asking for trouble in the future if only one tire fits my criteria now? (all others are e rated and I'm after comfort)

3) Are those Falken any good for street, or will their tread be too noisy, and slippery when wet?

4) No one else on here with a Denali seems to run 18s. Is there a reason for that, that I'm missing something here, and I should stick to only considering 20s?

Thanks for any additional thoughts.

You're really splitting hairs with these tire sizes. The big thing is to get the correct offset that's where it's going to make the biggest impact in terms of rubbing. From the 32.8 to 33 you're gaining .5" of overall circumference and about 1" overall in sidewall. So we're talking .25" gains front and back and .5" gains top to bottom. So if you have more that a 1/4" of gap in the tightest spot of turning Radius you should be just fine.

MrLeadFoot · March 14, 2023

3 hours ago, Homewrecker007 said:

You're really splitting hairs with these tire sizes. The big thing is to get the correct offset that's where it's going to make the biggest impact in terms of rubbing. From the 32.8 to 33 you're gaining .5" of overall circumference and about 1" overall in sidewall. So we're talking .25" gains front and back and .5" gains top to bottom. So if you have more that a 1/4" of gap in the tightest spot of turning Radius you should be just fine.

I guess I wasn't clear. I already know that 33" in diameter works on a 275/60/20, as that is an opttion that my model came with, and I recently tried them out, but I was referring to the 285/65/18. Although the 32.56" diameter would surely fit, I'm not sure if would it be too wide. Are you saying if I have more than a 1/4" gap, measured with my 275/50/22 now, that I should be fine with the width of the 285/65/18?

Edited March 14, 2023 by MrLeadFoot

Homewrecker007 · March 14, 2023

1 hour ago, MrLeadFoot said:

I guess I wasn't clear. I already know that 33" in diameter works on a 275/60/20, as that is an opttion that my model came with, and I recently tried them out, but I was referring to the 285/65/18. Although the 32.56" diameter would surely fit, I'm not sure if would it be too wide. Are you saying if I have more than a 1/4" gap, measured with my 275/50/22 now, that I should be fine with the width of the 285/65/18?

If you're going with factory wheels I believe it will be fine but a test fit before going all in would be good idea.

Here's the wheel specs for all 3 sizes.

Factory 18x8.5 Wheel Offset = +26 mm - Back Space = 5.77" Inches
Factory 20x9.0 Wheel Offset = +28 mm - Back Space = 6.10" Inches
Factory 22x9.0 Wheel Offset = +28 mm - Back Space = 6.10" Inches

MrLeadFoot · March 14, 2023

Thank you for the additional info. I think I might have to stick with the 20s, because I'm not sure how I would test fit 285/65/18 before buying someone's take-off 18s. I will do some more research with the info you gave me.