Many tire companies say a 275/40 will fit on a 8.5"

 

275's will still be fine.

 

im not against chrome per se, but on a white car with flat black accents, chrome seems to contrast the theme way too much, its just too shiny
polished aluminum is a balance between the chrome and the painted rims

basically, ive honed my car to look exactly as i want it (with a few minor details like the front turn signals and ride height left to be done) and the chrome would throw it out of whack in my eyes

if i didnt have the flat black accents, i'd go with painted black or black chrome bullitts and be done

 

so how much benefit would, say, 255 really give me?

 

I'm going with the 255/45/18 on Shelby bullits for my summer tires.
mich x-ice 235/50/18 on my stock fanblades for winter.

 

Nobody makes a set of wider bullits that look correct. they're always off enough and remind you that you look like the first camaro bumblebee from transformers.

For $400 you can get them widened and this is your BEST choice especially when you consider the cost of wider options and trying to sell a set of only two used bullitts

However you can also easily run 275 tires on the car. I've done so on the stock 18" bullitts but you're not going going to be able to find any tires that cost less than $600 for the pair. Which means there are probably higher priorities than this.

 

Joo,

A 255/45/18 tire that is Extreme Summer or Max Summer performance oriented will give you a very noticeable improvement in traction. Will it mean you will never tear them loose, nope, but it will be better. Your stock tire is an Ultra high performance all season tire with a 400 AA A rating. It is a harder compound tire.

My recommendation for you would be:
Goodyear Eagle F1 Supercar if price is an issue or
Pirelli PZero Rosso or Yokohoma ADVAN Sport if price is not an issue

These are all softer compounds 140AA A to 220AA A and are designed for maximum dry and wet traction but do poorly in colder and inclimate weather.

 

+1 the Yokohoma Advan's are amazing, I love them, that said I'm not looking forward to new tires in a few months...

 

i could have sworn i was hearing bad thngs about p-zeros when i first bought the car though...

 

Pirelli PZero Nero M&S are the stock 17" tire. I have them as my "winter" tire. They aren't that bad.

The PZero name is just like the Goodyear Eagle name, it doesn't tell you much about the tire. They make GY Eagle F1 supercar, Eagle F1 GS-D3, Eagle F1 Asymmetric, etc.