that thread is totally wrong. measure the circumference of a 190/55 and its bigger than a 180. that raises the rear as the OP said and that makes it steer faster. everything he said and was told is was from someone who obviously understands suspensions.
a good shock has an adjustable ride height, so it can be adjusted for different tire diameters and retain the riders prefered angle between the chassis pivot and the rear axle. also a 190/55 has more surface area so it provides more traction allowing one to pick the throttle up a little harder and earlier in a corner. many of the top club racers use 190's on 5.5" rims because of that. although many have tried it and dont like it much as well, try it and see.