tire question
 

new owner of 2013 silverado 1500 ext cab 5.3 v8 6 spd a/t etc
this truck came with 255/65/R17 tires
door plate says it should have 245/70/R17..
What are the consequences of this difference please?

The first number, in mm, is the width of the tire.

The second number is the percentage of the width that is the height of the sidewall.

The third number is the diameter of the rim in inches.

essentially,

The tires on it are 10mm wider than stock

the height of the current is 255x.65= 165.75--- x2 =331.5 + rim
height of stock is 245x.70= 171.5--- x2 =343 + rim

the total height of the tire is 11.5mm less than stock.

This is so insignificant I would not worry about it unless you can feel the tires rubbing when you turn them all the way, which you shouldn't

thank you for your prompt and useful reply