Are you just looking for stance? 275s will give a nice look.
Going any widerthan 275 will create a tendency for the car to plow in my experience....you can of course dial that back out but if you are interested in handling 275 is a really good width; I've run 275s (mostly 35 section but a couple 40s too)and got good results fromvarious tire mfgon 18x9.5s and I've also run 285s and frankly they were a PITA.
I generally don't run staggered unless I am cruising - then I think its in the Mustang bylaws you have to

 

so 275's for best handling? that's exactly what i needed to know. and those will fit on a 9" wide rim, correct? would you say 275/35/18's would be best or would you get a 40 section?

 

275's willfit on a 9" wheel but will work better on 9.5" or wider. Wider (wheels) = better support for the tread.

A 275/35 is a pretty short tire (25.6"). Think "possible ground clearance issues", especially if you're lowered.


A 255/45 is actually a pretty good tire choice for 9" or 9.5" wheels if handling is a priority (the GT500 front tire package is 255/45 on 9.5).Keep in mind that conventional appearance considerations (what most people think in terms of) are based on OE wheels that in most cases are sized a little narrower than what would provide the best performance. Trading away a little ultimate performance in the interest of things like improved ride quality, wheel cost, and more gradual breakaway up toward whatever limit is considered a preferred compromise for the average driver.


Norm

 

I had a conversation today with my brother and willshare his comments with you about 255s vs 275s. Heis a qualified Porsche Owner Club instructor with racing experience.

His recommendation was that for a track day newbie like me the 255s are a better choice as on them the transition from hanging on to sliding will be easier for me tolearn. Once I was proficient then I should be better able to handle the more abrupttransition of the 275s.

 

Your brother offers good advice actually, for a Porche driver

255s and a good DOT tire like BFG or Kumho will offer a good stable starting point until you get consistent with the car. Without the ability to provide smooth consistent steering and throttle/braking input, 275s will seem pretty inconsistent when in fact its just you.

With such words of advice I suspect your brother is NOT one of those "you can't trail brake a porche" drivers....if so keep listening to him

FYI, I generally run 275/35s - I am dropped 1" front and 1.5 rear. The other thing to consider is I usually run -2.5 degrees of camber.

 

With my Saleens and 275's up front, the only time I hear a rub is parking fast (breaking, and turning to park in front of my house). Very light touch, thats it.

 

No issues with rubbing.




[IMG]local://upfiles/50298/59E8289410644DB983F7B22334AB2CC5.jpg[/IMG]

[IMG]local://upfiles/50298/558AE3DAD8F545628F9275C68D85BF44.jpg[/IMG]

 

285/40 with fit up front with no to minimal rubbing and even if you are lowered

 

PonyGt/2005

To make sure I knew what trail braking was I looked it up and found this http://virtualracersedge.com/trail_braking.htm.

Sounds like fun and a good way to overcome the Mustang's inherent understeer.

 

OP, just remember that ponygt/2005 is running a smaller diameter than stock, a 275/35/18 is 25.6" diameter tire compared to your stock 27.1".

If you choose to go with a smaller diameter tire you will be essentially changing your rear gear. Since I don't see any listed in your sig, it will give you a nice bump. If you had 4.10s and ran a 275/35/18 tire you would be closer to 4.30s and you may not want this. Then again black S197 is running 4.30s and a 26.7" tire so he's at ~4.40s.

Also, running a smaller diameter tire will generate more wheel well gap so you may look like a 4x4 if you are not lowered a lot.