Jump to content
  • Sign up for FREE! Become a GM-Trucks.com Member Today!

    In 20 seconds you can become part of the worlds largest and oldest community discussing General Motors, Chevrolet and GMC branded pickups, crossovers, and SUVs. From buying research to owner support, join 1.5 MILLION GM Truck Enthusiasts every month who use GM-Trucks.com as a daily part of their ownership experience. 

Spare Tire Size?

Recommended Posts

Just ordered 2021 GMC SLT 6.6 Gas last week with 20" wheels. The order form only lists 17" or 18" spare tire options. This is not good for a 4WD and a limited slip rear when the spare is needed, no matter how far the drive is. The salesman just shrugged his shoulders when I asked.

Anyone have a  truck that came with factory 20" wheels and got a 20" spare instead of a 17" or 18"? 

Link to comment
Share on other sites

Exactly. It doesn't matter if the rim is a 17in or 18in. The tire diameter is going to be the same size as the 20in rim with tire.


They have been doing this for like 15+ years or more on trucks. The spare tire is always smaller in rim diameter on vehicles equipped with large 18's, 20's or 22's.

  • Like 1
Link to comment
Share on other sites

I'm about to order a 2021 3500HD SLT CC LB SRW, so I've been using the GMC build and price page quite a bit and looking at options.  Regardless of the wheels you order, the provided spare is 275/70-18, same as the standard wheel.  According to on line tire size calculators the diameter of a 275/70-18 is about 33.2 inches, and the diameter of the optional 275/65-20 is about 34.1 inches, for about a 2.8% difference. 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Create New...

Important Information

By using this site, you agree to our Terms of Use.