How Important Is the Offset (ET) of a Wheel During Wheel Upgrade for Various Cars?

Hi all,

I have searched Team BHP for answers with regards to the title of this thread and also on many ocassions posted this question but never got an answer for the same.

I have also noticed that in many threads regarding wheel upgrades, there are alot mentioning about the right size of rim for the car, right tyre size for that rim/car and also a seperate thread with regards to the right PCD for particular cars and many links to the ‘Wheel & Tyre Bible’ to help us with the same. Even though I agree that these are all important factors to be considered while upgrading your wheels, I have rarely seen the ‘recommended offset’ mentioned while doing so.

I have read on the internet that the ‘recommended offset’ is equally important as the other factors but rarely mentioned on this forum; so my questions are –

1. Does one stick to the original offset of the stock rim at the time of wheel upgrade?
2. How does one calculate the ‘recommended offset’ during a wheel upgrade.
3. How important is this figure?
4. What are the issues one can face if ‘recommended offset’ is not adhered to?
5. Stock offsets & recommended offset based on the best/recommended wheel upgrades for various cars.