I have the same problem with my Mach 1. I can make power and I can even get into the 3300 lb arena but with (edit: 265mm) now being the biggest tire available for the class. It is really hard to get the car to turn or even go straight when I put the pedal to the floor. I even wrote up a thread about ST V8 only cars where tire sizes could be bigger, basically big cars big power minus corvettes(for obvious reasons) I was more or less told until a few fully prepped V8 cars got killed all the time no one would take the idea seriously.
I hear ya. STX is an impossible enough battle with the 2005-2010 Mustang GT's 4.6L 3V power levels (300-315 hp stock), but with 2011-2013 5.0L 4V (412-444 hp stock) power levels it is a total joke. As in: I would highly suggest another class for anyone with a 2011+ Mustang GT. ESP is the only place worth racing these cars, but they've just ram-rodded some changes there that make it less than ideal place to race, at least for 2013 (80% of Watts Links just became illegal last month).
I do feel like there would be a number of 2005-2013+ Mustangs and even possibly some 4th and 5th gen Camaros + Challengers that would race in a "Pony Car" ST class. Hey, they have half a dozen classes for Miatas and almost as many for the AWD boost buggies, why not allow the popular V8 RWD cars a place to play on street tires? And as many of you know there are TWO NEW PONY CARS coming next year: The all-new 2015 Mustang and 2015 Camaro are supposed to both be all new, IRS equipped, smaller in width and length, and both targeted to be about 3300 pounds - with even more power. And there's a new Dodge pony car coming around the same time - the 2015 Baracuda, also rumored to be lighter/smaller. To say that these might be popular is a given. Add in the heavyweight RWD Genesis Coupe, the older SN95 Mustangs and 4th gen Camaro/Firebirds, and you have a pretty healthy class diversity of new and old cars.
We ran a similar Pony Car class in my college autox club (TAMSCC) in 1991-2000 and it was always huge... 25+ cars at local events. Rules were 275mm/200 UTQG max and little else, with almost 100% of the cars being Mustangs or Camaros. So much fun, and lots of freedom, but the tire width and compound limit kept power levels and costs in check. Now that the pony cars are heavier and faster I think the width limit would need to grow to 295 to 315mm, both of which fits the S197 chassis without fender mods.
These 295/35/18 tires on 18x10" wheels have lots of room - we use 18x11/12" wheels with 315mm rubber now
My daily driven 2013 GT has that 295mm tire and it has gobs of room, still. The many 265mm tires we tested and raced with on our STX classed 2011 GT (very unsuccessfully) look like temporary spares in comparison. And whoever said there aren't any good 18" diameter 265mm choices for STX needs to look harder: we used two different branded 265/40/18s, from Yokohama AD08 and Hankook R-S3. We also used 265/35/18s from Hankook, Toyo R1R and a Dunlop in 265/40/17 (on the rear only - the 17's wouldn't clear the front 14" brakes). That was almost 2 years ago now, and I wouldn't be surprised if there were more options now. Let's see... the Dunlop Direzza ZII comes in 265/35/18, and there's the Kumho XS in 265/35/18, and the Bridgestone RE-11A is about to drop and will likely have 265s. TONS of 265mm choices exist in the 140-200 UTQG range. :)
265/40/18 Yokohamas on stock sized 9" wide wheels look terribly small on this 73" wide, 3500 pound Mustang
I think ST classes should not have max tire sizes since we have a no fender change rule, whatever you can get inside of them with rolling should be the way it goes. Why is there a tire size rule anyway? I am a newbe so I have no clue how that rule came into effect. It only handicaps the larger cars which are already handicapped by weight anyway.
Well the tire width maximum was actually a clever way to "equalize" all of the cars within a given ST class. But this is the only category that does it this way, where ALL cars within a given class have the same width maximum. But two ST classes have two "maximums": One for RWD and one for AWD (see - STX and STU). For the most
part it kind of
works, and keeps the performances relatively the same... as long as the cars within a given class have similar weight levels.
Of course this isn't always the case.
The S197 Mustang (the only viable Pony car in the past 10 years) is a porker, and doesn't fit in any of the traditional ST classes. Its too heavy for the skinny 265mm tires and 9" wheels that are allowed there. This car does get a lot more driveable on wider wheels and tires allowed in STU (no wheel width limit and a 285mm limit for RWD cars), but they took that option away when they classed all cars in ONE class for ST, to keep the damned Honda Civics from class-jumping and dominating ALL ST classes in the least powerful (yet lightest) cars. I'm glad that happened, as the Honda class jumping kept a lot of racers out of STX and even STU for 2-3 years, but it ended up hurting the Mustang's ST potential, in the end.
I would rather see this car in STU, after tilting at windmills in STX for 2 seasons, spending many thousands of dollars testing every viable tire option and realizing that it couldn't even be competitive in the class regionally, much less Nationally (we tried and failed there, too). We ran a couple of events in STU trim and it was MUCH more competitive, but still pretty far behind a properly prepped EVO or STI. But at least on 10+" wheels and 285mm rubber it gets a lot more drive-able, and you can use that skinny pedal on the right a little. On STX's max width 9" wheels, notsomuch.
Our brief stint in STU was much more successful, netting our first top 10 PAX results in the car in 2 years
I don't think this car is any threat in STU, not by a long shot, but I would rather see at least the 2011+ 5.0L cars class in STU rather than STX - just to be able to use a 285mm tire. Or create this provisional "ST-Heavy" class and invite all of the porkers to play, and open up the tire width even more? That's a long shot, of course, as there aren't any pony car folks on the STAC and aren't many even trying to race these cars in STX (except a few die-hards). Not blaming anyone, as these guys aren't knocking the SCCA door down and don't whine as loudly as the Miata/Honda guys. :D
I am building the car to "see" if I can be competitive this year but I have a feeling I will end up in ESP next year. At least the suspension rules are the same!
Well... STX and ESP suspension rules are mostly
the same. Don't get me started.
But yes, by all means necessary, switch to ESP if you are at all serious. The competitiveness jump we saw from switching up in tire width (STX -> STU) and then compound (STU -> ESP) was dramatic. We went from rarely cracking the top 20 in PAX locally in STX to 7th in STU to top 2 in ESP, with virtually no other changes other than the wheels and tires! Racing against the same people every month, but the wider and then MUCH wider tire bumps just made the car easier to drive and faster in PAX and class standings. ESP is the only place to play for a streetable S197 Mustang, in my view. FStock has too many painful restrictions (stock ride height springs, no camber) and STX just handicaps the car on too skinny of a tire.
Left: 3 of 4 ST legal tire sets we tested in one day on our STX Mustang: Right: Just a few of the R-compounds we tried in ESP
But if you think tire costs were expensive in STX (and they were for us, mostly due to the wide number of options we purchased and tested with), go price a 315/30/18 Hoosier A6. And now plan on about 30 runs per set. The math isn't pretty, but it sure is a lot faster and more fun!
Dang... sorry for the threadjack.