If one upsizes a wheel, what should be the drop in profile to keep the same rolling diameter?

For example, when upsizing from a 16in rim with a 55 series tire (RSX rim & tire size) to a 17 in rim, what should the appropriate drop in profile of the tire?

Also, is there a simple thumbrule one can go by calculating this, so I know what profile tire to pick for other rim sizes/profiles?

 

Usually the general idea is when u are upsizing a rim, you would downgrade ypur profile in intervals of 10, if you are increasing the rim size by 1 inch, I.E. a 16 inch stock rim with 55 series tires would now become a 17 inch rim with 45 series tires, etc, so on and so forth, soembody correct me if im wrong, good luck. Ron

 

Yup, the "plus" sizing is to add 1 to the rim size and subtract 10 from the aspect ratio. I came to this conclusion after a little while on the calculator ... should have just asked here

I think the rule for plus sizing is that you should keep the overall diameter within about 3% of stock (can vary diameter by as much as 3/4 inch in some cases). This will keep you from having to recalibrate your speedometer and such. Just watch out for the width of the tires, some might rub even if the diameter fits.