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OEM 17” vs 20” HD wheels and tires


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I have a 22 Custom and it’s almost time for new tires. I’m not a huge fan of my custom wheels and have been looking to upgrade to a higher level OEM wheel set. Has anyone driven these trucks with both 17” and 20” wheels. Is there a noticeable improvement in off road dampening with more sidewall or does it not matter with the E rated tires? 
 

thanks

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Ride would be close to the same if not the same.

 

What would change big time is the speedo.  The stock 20s LT275/65R20 is a 34.1" tire, the stock 17s are LT245/75R17 or LT265/70R17 which are a 31.6" tire.  Sidewall height is within .3" of each other.  7" for the 20s, 7.3" on the 17s.  

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The stock 18" tires which came on my AT4 will have the most sidewall of these 3 tire sizes as it is 275/70 R18. I had to select many of my options separately to avoid the 20" tires which came with the preferred package as I did not want the 20" tires.

The stock 18" tire has a sidewall height of 7.6" instead of 7.3" and 7" for the other 2 tire sizes mentioned. So, for me it was a big difference between the 18" and the 20" tires (about 10% difference). For you it would be a .3" difference on the sidewall.

But the 18" does have a diameter of 33.2", which is 1.6" larger than your current tire. However, your speedometer can be recalibrated by the dealer for different size tires. They do the same thing at the factory when the vehicle is assembled.

Another option is to keep your current wheels and get tires with a larger aspect ratio. Then have the speedometer recalibrated for the new tire diameter. This method would allow you to get the most sidewall before having rubbing issues on the fenders/linings. Some dealers will do it. There are other ways as well. But the speedometer error is only 3 mph at 60 mph for changing the tire diameter by about 1.5". So there's no reason why you couldn't drive like that if you wanted to.

Just be aware that more sidewall means less handling in corners.

Edited by Dr1ft3r
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Yeah I have the stock 18” and would never personally want 20” wheels on a pickup. I prefer to look and road feel of more sidewall on a truck. 
 

now for a sports car I prefer the low profile look. 

Edited by Pryme
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8 hours ago, Dr1ft3r said:

The stock 18" tires which came on my AT4 will have the most sidewall of these 3 tire sizes as it is 275/70 R18. I had to select many of my options separately to avoid the 20" tires which came with the preferred package as I did not want the 20" tires.

The stock 18" tire has a sidewall height of 7.6" instead of 7.3" and 7" for the other 2 tire sizes mentioned. So, for me it was a big difference between the 18" and the 20" tires (about 10% difference). For you it would be a .3" difference on the sidewall.

But the 18" does have a diameter of 33.2", which is 1.6" larger than your current tire. However, your speedometer can be recalibrated by the dealer for different size tires. They do the same thing at the factory when the vehicle is assembled.
 

 

 

OP has a Custom which comes with 20s so the 18s are smaller by 0.9".  275/65R20 is 34.1", 275/70R18 is 33.2".

 

Dealer can only calibrate to tire sizes that are optional by trim.  So on an LT, they come standard with 17s, 18 and 20 are optional.  If the truck was built with 17s and could have been configured when ordered with 18s or 20s, GM will be able to issue a calibration.  All Customs come with 20s and that's the only wheel/tire combo available so they won't offer a calibration for any other factory size because they only come with 20s.  

Edited by newdude
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4 hours ago, newdude said:

 

 

OP has a Custom which comes with 20s so the 18s are smaller by 0.9".  275/65R20 is 34.1", 275/70R18 is 33.2".

 

Dealer can only calibrate to tire sizes that are optional by trim.  So on an LT, they come standard with 17s, 18 and 20 are optional.  If the truck was built with 17s and could have been configured when ordered with 18s or 20s, GM will be able to issue a calibration.  All Customs come with 20s and that's the only wheel/tire combo available so they won't offer a calibration for any other factory size because they only come with 20s.  

 

Oh, my mistake. I thought he had the 17s. 18s still have more sidewall than the 20s (.6" more sidewall).

Lots of people run much larger tires as well as lifting their trucks to accommodate those larger tires. There are aftermarket shops which can recalibrate the speedometer. It's not very expensive at all, usually around $100.

Edited by Dr1ft3r
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Cant stand anything less than 18in on a truck, and to me 20s look the best by filling th wheel well.  my 2022 AT4 had stock 18s and bought and replaced them with stock 20s,  didnt notice the difference on the speedo, checked with GPS.  Sidewalls on the stock 18s were taller, so the overall difference was minimal 

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