20" wheels on crew cabs

GM-Tech · April 1, 2005

This topic has been a hot one with a lot of opinions but no real answers. So, I put a call into my contacts and got as much of the story as was possible. I'm not at liberty to reveal my sources, but they come from the highest levels.

You can chose to believe this or not. I'm not going to debate this, I'm just passing on what I believe to be an accurate answer from the horses mouth, so to speak.

1. The long term durability issue with 20" wheels on crew cabs has to do with wear of a rear spring bracket that engineering expects may occur at some point BEYOND THE USEFUL LIFE OF THE VEHICLE.

2. The issue is a noise issue, it is NOT safety related.

I was not able to get the definitive answer as to what is the "useful life" of one of our trucks, but they know that some will drive their trucks well beyond this arbitrary figure. I also couldn't get exactly where the wear occurs, but it sounded like it was probably the spring's front bushing where it is located in the frame bracket. As this bracket is part of the frame, there is no way to repair it in GM's eyes. Wear to that bracket would require frame replacement.

These are the reasons they are telling us, "If you already have a customer with a crew cab riding around with 20's that you've installed, it is not necessary to call them back and restore the vehicle to its stock configuration." They'll probably never experience the problem. However, they feel it's enough of an issue not to intentionally continue to do these installations on crew cabs.

Personally, I think GM is just gun shy because of the expectation that they are responsible for anything that may occur years and years down the road. 10 years down the road they don't want to have to be recalling vehicles their dealers put these wheels on because customers are screaming, "You should have known!" and filing complaints with the NHTSA.

So if you want to put 20's on your crew cab, the odds of a problem developing are slim to none. On the other hand, YOUR dealer won't have this information and you telling them some guy on the Internet told you this will probably get you a blank stare. ANY suspension problems that occur will probably be blamed on your aftermarket wheels. Plus, we still wouldn't be able to update calibrations because GM won't provide them if it is a crew cab.

So there you go. Believe it or not. It's your choice.

MS3DALE · April 1, 2005

Good post GM-Tech,You got more info. on your end than I got on mine,Of course I didn't really try to get any info. with my sources at GM.

The "You should have known" complaint is what I was worried about with some customers,I've heard it all to often as I'm sure you have too.

GM Dude · April 8, 2005

GM-Tech

Thanks for that info as it is what I have suspected all along. I always felt if it was a real safety issue it would have been delt with differently. Of course it was a little too late because I already filed a complaint with Auto Line to get an answer since it was not coming from customer service and we'll see if the stories match, if I get one.

Again, thanks for that info.

y2kz71 · June 28, 2005

Isnt the frame and suspension of an extcab and a CC the exact same?

Why is it okay for the extcabs and notthe CC's?

I just bought an 05 CC last week and am considering getting 20's but now Im not so sure. However, the dealer I purchased from had a CC on the showroom floor with aftermarket 20's so are you really sure about this policy?

Frank S · June 28, 2005

Isnt the frame and suspension of an extcab and a CC the exact same?
Why is it okay for the extcabs and notthe CC's?

I just bought an 05 CC last week and am considering getting 20's but now Im not so sure. However, the dealer I purchased from had a CC on the showroom floor with aftermarket 20's so are you really sure about this policy?

<{POST_SNAPBACK}>

Oh he's positive about the policy but I've heard tell that the issue has been resolved from a salesperson that we work with very often. He was also aware of the issue and smiled last week when I brought it up in a conversation but said it is indeed ok to add 20's to a 1500 CC now.

Not sure if this is true or not. Maybe The Man here can shed a little more light on it.

MS3DALE · June 28, 2005

No,The frame on an ext.cab and a crew-cab are not the same,The cab mounts and front spring hangers are different.

And yes,You are OK to put 20's on now,GM lifted the restriction.

GM-Tech · June 29, 2005

Isnt the frame and suspension of an extcab and a CC the exact same?
Why is it okay for the extcabs and notthe CC's?

I just bought an 05 CC last week and am considering getting 20's but now Im not so sure. However, the dealer I purchased from had a CC on the showroom floor with aftermarket 20's so are you really sure about this policy?

Something is different about the crew vs. extended cab. I don't know what. As for the policy... oh yeah, I'm sure about it. HOWEVER, GM made the needed changes at a certain VIN breakpoint of 2005 crew cabs, so if the VIN is beyond that breakpoint, the issue no longer exists and the wheels can be installed.

In fact, we just put 20's on a 2005 Crew Cab today and I called and got the calibrations needed for the PCM without a hitch. Obviously, its VIN was beyond the breakpoint.

GM-Tech · June 29, 2005

And yes,You are OK to put 20's on now,GM lifted the restriction.

If it's beyond the aforementioned breakpoint. I'll find that TSB and post it here. I just looked at it again today to check on the 2005 we were upgrading.

GM-Tech · June 29, 2005

Here's the pertinent information...

On October 19th, 2004, a "Stop Sell" was placed on 20-Inch Plus-Size Wheels offered as Chevrolet and GMC Accessories for the 1500 Series Crew Cab models of the Chevrolet Silverado and GMC Sierra (Models CC15543, CK15543, TC15543, TK15543).

However, component design changes have recently been made to these vehicles at the following VIN breakpoints, allowing for installation of the 20-Inch Plus-Size Wheels:

1500 Series Crew Cab Model

VIN Breakpoint

Merchandising Model

Sierra (2WD)

51334993

TC15543

Sierra (4WD)

51334978

TK15543

Sierra Denali (AWD)

51334762

TK15543

Silverado (2WD)

51334946

CC15543

Silverado (4WD)

51335001

CK15543

Note: The 20-Inch Plus-Size Wheels should continue to be restricted for 2004-05 model year 1500 Series Crew Cab models built prior to these VIN breakpoints. The only exception is for those customers who had 20-Inch Plus-Size Wheels installed on their 1500 Series Crew Cab model vehicles prior to October 19th, 2004.