timw wrote:Is wider always better? I thought for a momentum car diminishing returns rise pretty quickly with regards to wheel weight and rotational inertia, no? I am in the same boat, trying to decide on Rivals at 225/45 with the 3% speedo error or the 235/40 dunlops. Keeping it down at the 205/45 wheel/tire weight becomes a challenge (read $) with wheels given the heavier (and outward heavier) tires.
From my own personal experience in street driving, autox, and lapping days using 3 different tire sizes on a stock powered NC (205/45/17, 215/45/17, 235/40/17), I would say that even the small jump in taller gearing from 205 to 215 was noticeable, but not really significant. With the 225/45 tire being even taller, I suspect the loss of torque is going to be more pronounced.
Further more, with 235/40, I definitely notice the extra weight in the tires (the 17x8 PF01 I use are the same weight as the OE 17x7 wheels), but at least the effective gearing ratio remains the same. So with a 225/45 tire, I suspect that you'd get hit with 2 penalties -- 1) taller effective gear, meaning less torque and slower acceleration, and 2) greater tire weight, which again means slower acceleration.
As far as lateral grip and stability between the 235/40 and 225/45 are concerned, the clear winner is going to be the 235/40.
Last but not least, from the 225/45 pictures that I've seen, I would say that the tire fills out the wheel well a little too much. The 235/40 has a more aggressive look that doesn't seem out of place.
This is why I prefer a 235/40/17 over 225/45/17 on the NC. Unfortunately, tire selection is a lot poorer with the 235/40/17, so you might want to take that into consideration as well.
What God has united, let men not divide.