Tires

[Kpenn50]

I recently installed a 4 inch ready lift on my 2916 Sierra 1500. New tire size is 305x55x20.. I still have the stick spare tire, 275x55R20. 
my question is what happens if I need to install the spare while driving? How will it affect the drive? 

[Salsa De Piña]

Did trucks with the 20" wheel option come with a 20" spare?  Considering all the cost-cutting, that surprises me.

 

If it truly is a 275x55R20 spare, then it's only a 4% difference in diameter.  Don't put it in 4 wheel drive and you'll be just fine.  If you get a flat on the rear, your differential will be getting a little workout so maybe swap the spare to the front axle to avoid that if you're going to be driving on it for a while.

[CamGTP]

Even trucks with 20's came with a 17in spare that matches the size of the 275/55/20 diameter.

[MikeBMW]

12 hours ago, Kpenn50 said:

I recently installed a 4 inch ready lift on my 2916 Sierra 1500. New tire size is 305x55x20.. I still have the stick spare tire, 275x55R20. 
my question is what happens if I need to install the spare while driving? How will it affect the drive? 

The spare will get you to a place for repair.
Don't do any highway high speed miles in the interim.

Edited September 16, 2021 by MikeBMW