Have a 2010 Ext Cab with 20" tires and wheels out of the factory. Don't really like them and don't want to pay a fortune for new tires. I have a whole set of 17's off of another 2010 Silverado that I am thinking about swapping. Is there any kind of issues other than speedometer that I may be missing? Everyone talks about going up in size but not down...

 

The stock size 20 and the stock size 17 are exactly the same overall diameter. Means speedometer will be the same

 

yup, just swap em and don't worry about anything.

 

Check the tires but I would bet that the 17" tires have a higher load capacity than the 20's.

 

Exactly what I thought....thanks for the second opinions.