Tires: Downgrade in tire speed ratings, Tire Speed Rating

Question
I have a 2007 Nissan Maxima with 225/55R17, V speed rating tires and am a non-aggressive driver. Everything I have read says a switch down in speed rating will offer a more comfortable ride. Lower speed rating will save me about $10 a tire. I priced tires and Costco was the best deal on the tire I am wanting which is the Michelin Primacy MXV4 but Costco will not mount anything under the original speed rating of V. A few questions: Would I be able to tell the difference between a V and an H? Will downgrading in speed rating offer me a more comfortable ride, longer tread life or anything else? Costco mentioned the Maxima needs a V because of the suspension and braking issues. Is that true? Any information on pros and cons to downgrading/not downgrading speed rating you have would help me out in making my decision. Thank you very much in advance.

Answer
Jay,

First, changing tires - even within the same size and speed rating - can have a profound effect - much more than some folks realize.  For this reason, it is difficult to make statements that stand up to scrutiny about changes in tire size , changes in speed rating, etc.  The best I can do is to explain the direction a particular change would make.

As a general rule, going down in speed rating does result in a slightly better ride, a slightly better wear rate, slightly less traction, some loss in handling, and slightly better fuel economy.  But remember, this is direction.