The expiration date of sour cream is just used as a general guideline and lets you know when you should use it up by before it loses it's freshness.
The expiration date of the sour cream doesn't mean the sour cream has gone bad or is no longer safe to eat.
As long as the expired sour cream has remained remained refrigerated then the sour cream is safe to eat as long as it smells good and has no bad mold or anything else in it.
If it smells bad or you take a bite of the sour cream and it tastes bad then throw it out and don't risk your health.
But if it taste good and smells good and has no mold in the sour cream you can safely eat it even though the sour cream has expired.
I've eaten expired sour cream a lot and never gotten sick from it as long as I've kept it refrigerated.
Sour cream should last a few weeks to a month past it's expiration date as long as it remains refrigerated.