Up coming Auto X season

[I am Legend]

First off, just want to say hello, this is my first post although I have been lurking around this forum for a while. I love that fact that there is an area specifically to road racing/autocross/etc. Most other mustang forums are so focused on getting these cars down a track in a straight line.

So down to business, I have a 2006 GT and I am getting plans ready for the upcoming autocross season. I bought the car last fall and ran two events in F-stock on my "off the showroom floor" all-season tires. Needless to say, I had an issue with grip. For this year I am still planning on running in the stock class so modifications are limited.

I have read a lot of the tire related questions and comments on here and I am a little confused with what size tires I can actually fit. I have the stock 17x9 bullitt wheels on the car right now and plan on running those. So I would like to find out what size tires I can run or should I run? 255’s? Larger? I don’t want to stagger tires; I would like to keep the same size on all 4 corners. Also what tires do people like, use, etc, that have a 140 tread wear minimum?

 

[sean858]

I had good luck with Nitto NT05s on my Mazadspeed3 before my '11 but I'm sure the more experienced people here will have better suggestions. As for tire size I know you can safely run 275/40 17s on a 17x9 but that setup caused some tramling on my 01 GT back in the day, not sure how it'll work on an S197.

 

[Norm Peterson]

Are you sure about the OE 17" wheels being 9" wide? Or are you measuring the overall wheel width, outside to outside?

I'm under the impression that the OE 17's were 8" wide (measured between the bead seats, inside), which probably would measure about 9" overall.

Get this little detail straightened out first because your FS-legality depends on it. As a novice or until you start winning, it might be "winked at" even if it isn't legal. But not after you start showing some success.


You'll probably find out that what you can get away with running for tire size to wheel width for a minute at a time on an autocross lot is not something that you should be living with on a daily basis. Yes, the autocrossing is more intense. But the duration of each run is very short compared to, say, a drive from your house down to the Cape and back. IOW, you can "cheat" the minimum recommended wheel width a bit for autocross-only use, but really shouldn't for the daily stuff.


Norm

 

[JesseW.]

I'd put the widest tire possible on it. 285's all the way around would be nice. I think Sam Strano said he did that on some 8 inch wide wheels and had the best times that way. You can run R-compounds, but if cost is an issue, then go with a 140 treadwear.

As far as other mods, an adjustable front sway bar and shocks are about it suspension wise. you can also run a cat-back and a drop in K&N Filter.

 

[FR500GT]

I'd put the widest tire possible on it. 285's all the way around would be nice. I think Sam Strano said he did that on some 8 inch wide wheels and had the best times that way.

You sure about this?

 

[Sam Strano]

First, stock 17" GT wheels are 8" wide, not 9. And on those I ran 275/40-17's for r-comps. Stock 18's on the Shelby are 8.5" wide and I ran/run 295/30-18's on those. Stock on my 2011 are 19x9, and I ran 295/30-19's on those. These are all the tires I compete on. I didn't run these as street sizes.

 

[Norm Peterson]

Like I said a couple of posts back, what you can get away with for the very short durations that represent each autocross run does not necessarily match up with what you need for driving in general.

I think at one point Sam was running 285/30-18 R compound tires on the stock 18" wheels, which are 8.5" wide. Normally, that tire size calls for a 10" - 11" wide wheel, but the brief duration of an autocross run and the extremely short tire life (in terms of total miles) mean that you can get away with it.

It is possible for your times to improve with a setup that's outside the normal tire to wheel guidelines, but that does not mean that it will be as easy for a novice to drive the car that way. Nor does it mean that 285/30 is going to be faster on 8.5" wheels than on 10" or 11" (assuming that you can fit the wider wheels).


Let me suggest starting out with a good summer performance tire in a size that doesn't put your wheels below its minimum recommended width. You can learn some bad habits starting out on R-comps because their better grip will cover up some of your mistakes. Make that 'urge'.


Norm

 

[FR500GT]

I take back my statement about Sam running these haha

 

[Grip]

First, stock 17" GT wheels are 8" wide, not 9. And on those I ran 275/40-17's for r-comps. Stock 18's on the Shelby are 8.5" wide and I ran/run 295/30-18's on those. Stock on my 2011 are 19x9, and I ran 295/30-19's on those. These are all the tires I compete on. I didn't run these as street sizes.

Are you really using all the tread with those combinations? Or, have I been wrongly educated?

 

[Norm Peterson]

It doesn't matter whether you're using all of the tread, as long as however much of it that you are using is letting you go faster. And for doing well in FS, all you have to be is faster than the guy in an otherwise identical car but with smaller tires to have made it worthwhile.

Stock category doesn't let you indulge in selecting technically optimum-width wheels for the tire size needed, which leaves you with testing various tires and sizes on the wheels that you are allowed to run until you find what seems to work best. Or with finding out what the fast guys in your class are running and just copying them.

Places like ESP and CP are where you get to play with wheel widths that are more "proper" for the tire sizes that these rather heavy cars need.


Norm

 

[Sam Strano]

Are you really using all the tread with those combinations? Or, have I been wrongly educated?

I have run all those (and a few other) combinations on 3 different F-Stock Mustangs since 2006. Two normal GT's, the Shelby GT, and my 2011. The rim sizes on then are generally not interchangeable--legally. So what I ran on the Shelby could not have been run on the '05 GT, or my '11. I could run it on my '07 GT (and did) because 18x8.5's were an option on that car.

 

[I am Legend]

Thank you for the responses. First off let me clarify, I meant to say on the first post 17x8's. 17x9's was a typo on my part. I apologize for the confusion. Now that being said, I'm not looking to run R-compounds just yet, I will be very happy running some extreme performance/summer performance tires and in my mind’s eye, should be leaps and bounds better than the stock 235/55/17 all seasons that are on there now.

Sam, you mentioned that you ran 275/40's. Was that all the way around or out back?

 

[Sam Strano]

All the way around... on 17x8's.. did that both with SN95 and S197 chassis.

 

[KillrStang]

ok well i guess while we are on the topic, id like to ask a similliar question. i run a 18x8 rim with some tiny tires(225/45/18). i have already decided to move to a bigger tire such as a continental extreme DWS (255/45?). Should I go with a bigger rim as well? The next rim size in the style rim i have is a 19x10. id like to here some opinions, from a street and auto x perspective. thanx

sorry im new to the auto x (2 events under my belt) scene but i lack the technical knowledge i need to be better