285's vs 275's

Originally Posted by bdavis89

From the above link:

"Section Width

Following the letter(s) that identify the type of vehicle and/or type of service for which the tire was designed, the three-digit numeric portion identifies the tire's "Section Width" (cross section) in millimeters.

P225/50R16 91S

The 225 indicates this tire is 225 millimeters across from the widest point of its outer sidewall to the widest point of its inner sidewall when mounted and measured on a specified width wheel. This measurement is also referred to as the tire's section width."

Therefore, 285mm - 275mm = 10mm = 1cm = 0.4in = just a little less than half an inch wider. Right? Or am I missing something?