In today’s Sunday paper your column on tires for a VW made a major mistake.
You stated that the aspex ration set the tire diameter and a 175, 185, and 195 section all with an aspect ration of 75 would have the same outer diameter.
WRONG the section height is a factor of the section width times the aspect ration.
So the 175 x .75 has a height of 131.25, the 185 a height of 138.75 and the 195 a height of 146.25.
It is common to drop aspect ratio when going to a wider section tire to maintain the same outer diameter.