While at a driving school in Utah I was able to participate in an interesting exercise involving different tire and wheel sizes.
Three identical Ford Mustang GT's were outfitting with different tire and wheel packages.
Car #1 was fitted with OE 17x8 wheels with 235/55-17 tires
Car #2 was on 18x9.5 Ford wheels with 245/45-18 tires
Car #3 sat on the same 18x9.5" wheels with 285/40-18 tire
We then ran them through a very tight AutoX course. The results surprised most of the participants.
Car #1 predictably under-steered but, was easy to control and push to the limits of traction and sometimes beyond them.
Car #2 was razor sharp when responding to any driver input. It offered the best feedback allowing for the fastest lap times for all of the participants.
Car #3 Taking off the added width and straight line grip was immediately apparent. We also noticed more grip in steady state cornering but, the car felt very vague as all driver inputs were met with delayed response and a sluggish feel. When you are missing your marks due to sidewall deflection inconsistencies it can be very unnerving especially at speed.
So, in the end the 245 width tire on car #2 was able to turn faster laps than car #3 even though the tire was about 1.5" narrower. From an appearance stand point those 285's on car #3 did have an aggressive / muscular stance.
So, the answer to the question "is a wider tire always better" it depends. Most of the time a wider tire will offer better performance and cornering but, not always. Without the correct supporting mods and or parts wider tires may not always produce the desired results. Remember to ask yourself what you are wanting to do with your car and how you are going to maximize the use of the added width if you choose to go that route.
here's a couple of other pictures just for fun
the first view of my school steed
and after a couple days we became old friends
the last days "graduate" ride !!!
and I highly recommend the Ford Racing School at Miller Motorsports