Need Some Help With Autocross Wheels and Tires

HeavyMetalMonk · Dec 18, 2017

Hi guys,
Stopped by a race yesterday while waiting for my '18. I'm sold.

I'm considering getting a set of tires and wheels just for autocross. I have an 18 GT PP 10a on order. I've read 18" may be better, but I'm not up to speed on all the options.
Only mods will be H-Pipe and E85 tune- I believe I'll be in F-Street?

Anyway, can you guys lead me in the right direction for what I should be looking for in a set of wheels and tires? Or is my best bet to use the stock PP setup and just accept I will be replacing the tires more often?
I'm not on a SUPER tight budget, but I'm also not going to drop a ton of money on this either.

Thanks for the help

Grintch · Dec 18, 2017

E-85 is not FS legal.

Wheels in FS have to be stock width, +/- 1" diameter, and close to stock offset. So aftermarket wheels allow you to cut weight, and push out the offset a little (up to 1/4").

RE71R in 275 or 285 seems to be the tire of choice. In am not sure they are available in the right sizes for 18" wheels (though that would generally be best for cost and weight). Most FS Mustangs I have seen are running 19".

Run the car stock a few times and figure out if FS is where you want to be. Personally I find the street rules too restrictive. You wouldn't want to buy FS specific wheels and decide a few months later that you want to go ST, SP, or CAM - where you will want wider wheels.

HeavyMetalMonk · Dec 18, 2017

Thanks for the info!

SteveW · Dec 18, 2017

This page looks like a good summary of what the different categories are about as well as some basic info on the allowances without going deep into the rulebook:

https://ccrscca.com/autocrosssolo/car-classing/#streetclass

DickR · Dec 18, 2017

SteveW said:
This page looks like a good summary of what the different categories are about as well as some basic info on the allowances without going deep into the rulebook:

https://ccrscca.com/autocrosssolo/car-classing/#streetclass

What part of CA? I got my start in the SF area in the mid 70's before moving to Raleigh in 1986.

Similar document directly from SCCA.

https://dk1xgl0d43mu1.cloudfront.ne...ference-of-Category-Allowances.pdf?1485463261

You will find that an 18 GT PP with 10A will be pretty close to ideal for FS autocrossing as delivered. The oem Michelin tires will be very good until you decide whether you actually enjoy autocrossing enough to buy a second set of wheels for autocross tires such as Bridgestone RE-71R's or possibly and new Dunlop coming soon. With the 10A gearing will NOT be an issue like it has been with the 15 - 17 Manuals so no need to even think about changing to 18 inch wheels.

No need for more power from E85 even if it were legal (it isn't as noted above). Focus on driving schools first because that is where the speed in autocross can be found.

Show up an event and talk with the other FS drivers and try to get a ride with them in either their car or yours.

One MAJOR advantage of staying in Street class with a competitive car like yours will be until YOU get fast is that in popular cars like FS you know that the "slowness" is YOU rather than the car. I learned this decades ago when I was new and it took awhile for me to get fast. Now I'm old and getting slower all the time even though guys in identical cars are fast.

My 18 GTPP 10A with MagneRide will be assembled this week and will replace my 15 GTPP manual.

NightmareMoon · Dec 18, 2017

Initially, its best to run your stock wheels and tires for a few events, to make sure its something you want to pursue. Usually novices aren't so hard on tires that its a problem.

Later, if you can afford it, buy some RE71R tires for your /stock/ PP wheels with dedicated Autox rubber on them (aka RE71R in 285/35R19), which keeps you completely FS legal

Then move your stock MP4S tires to some nice street wheels with whatever sizes or offsets suit you for daily use. Something like a 19x10" square wheels or a 10"/11" staggered setup. You can put your current MP4S stock tires on these new wheels. Your stock 255/275 tires should fit on a square 10" or staggered 10/11" wheels with no issues.

You can get aftermarket FS-legal wheels, but there aren't very many good options which fit all three requirements of being the same exact widths as stock (9"F, 9.5"R), within stock offsets +-7mm, and also lighter than stock, so most people put the autox rubber on their stock wheels and buy something else for daily street use.

FWIW, if you do buy dedicated street wheels and sticking with autox for a while, you'll eventually save enough money not burning through two sets of tires a year from autox+street use on the same tires, but it may take 4-5 sets of tires to break even.

Make sense?

HeavyMetalMonk · Dec 18, 2017

NightmareMoon said:
Initially, its best to run your stock wheels and tires for a few events, to make sure its something you want to pursue. Usually novices aren't so hard on tires that its a problem.

Later, if you can afford it, buy some RE71R tires for your /stock/ PP wheels with dedicated Autox rubber on them (aka RE71R in 285/35R19), which keeps you completely FS legal

Then move your stock MP4S tires to some nice street wheels with whatever sizes or offsets suit you for daily use. Something like a 19x10" square wheels or a 10"/11" staggered setup. You can put your current MP4S stock tires on these new wheels. Your stock 255/275 tires should fit on a square 10" or staggered 10/11" wheels with no issues.

You can get aftermarket FS-legal wheels, but there aren't very many good options which fit all three requirements of being the same exact widths as stock (9"F, 9.5"R), within stock offsets +-7mm, and also lighter than stock, so most people put the autox rubber on their stock wheels and buy something else for daily street use.

FWIW, if you do buy dedicated street wheels and sticking with autox for a while, you'll eventually save enough money not burning through two sets of tires a year from autox+street use on the same tires, but it may take 4-5 sets of tires to break even.

Make sense?

Wow, thanks for the info. Yes...I think it makes sense lol. I am definitely going to run a few events to see if I like it enough to pursue.

If I do an e85 tune, I can't run in FS anyway right? So, would it make sense to go to a different class and if I'm going to get aftermarket wheels and tires just get the best ones I can afford and stay within that new class?
So I'd keep the PP wheels and tires for street use and get something different better suited to autox? (edit- AFTER I run a few stock events stock in FS)
I could also revert to factory tune and 91 for races I guess if that's a better option to start with.

(I'm not really concerned with breaking even, but I'm not really keen on dumping tons of cash into it either).

HeavyMetalMonk · Dec 18, 2017

DickR said:
What part of CA? I got my start in the SF area in the mid 70's before moving to Raleigh in 1986.

Similar document directly from SCCA.

https://dk1xgl0d43mu1.cloudfront.ne...ference-of-Category-Allowances.pdf?1485463261

You will find that an 18 GT PP with 10A will be pretty close to ideal for FS autocrossing as delivered. The oem Michelin tires will be very good until you decide whether you actually enjoy autocrossing enough to buy a second set of wheels for autocross tires such as Bridgestone RE-71R's or possibly and new Dunlop coming soon. With the 10A gearing will NOT be an issue like it has been with the 15 - 17 Manuals so no need to even think about changing to 18 inch wheels.

No need for more power from E85 even if it were legal (it isn't as noted above). Focus on driving schools first because that is where the speed in autocross can be found.

Show up an event and talk with the other FS drivers and try to get a ride with them in either their car or yours.

One MAJOR advantage of staying in Street class with a competitive car like yours will be until YOU get fast is that in popular cars like FS you know that the "slowness" is YOU rather than the car. I learned this decades ago when I was new and it took awhile for me to get fast. Now I'm old and getting slower all the time even though guys in identical cars are fast.

My 18 GTPP 10A with MagneRide will be assembled this week and will replace my 15 GTPP manual.

Thanks man, I initially missed your post. I get what you're saying, and it makes a lot of sense to stay competitive in FS instead of bumping up and getting smoked in another class. I suppose I will revert to stock tune for races and run 91 (or can I leave the tune and just fill up with 91?).

I'm in North County SD and will race in SD.

BmacIL · Dec 18, 2017

NightmareMoon said:
Initially, its best to run your stock wheels and tires for a few events, to make sure its something you want to pursue. Usually novices aren't so hard on tires that its a problem.

Later, if you can afford it, buy some RE71R tires for your /stock/ PP wheels with dedicated Autox rubber on them (aka RE71R in 285/35R19), which keeps you completely FS legal

Then move your stock MP4S tires to some nice street wheels with whatever sizes or offsets suit you for daily use. Something like a 19x10" square wheels or a 10"/11" staggered setup. You can put your current MP4S stock tires on these new wheels. Your stock 255/275 tires should fit on a square 10" or staggered 10/11" wheels with no issues.

You can get aftermarket FS-legal wheels, but there aren't very many good options which fit all three requirements of being the same exact widths as stock (9"F, 9.5"R), within stock offsets +-7mm, and also lighter than stock, so most people put the autox rubber on their stock wheels and buy something else for daily street use.

FWIW, if you do buy dedicated street wheels and sticking with autox for a while, you'll eventually save enough money not burning through two sets of tires a year from autox+street use on the same tires, but it may take 4-5 sets of tires to break even.

Make sense?

Excellent, excellent advice here.

NightmareMoon · Dec 19, 2017

yeah F-Street doesnt allow a tune, only a narrow few select mods.

STP class allows tunes and a few more mods, but the cars are expected to be faster and the mods required to compete get a bit pricey.

CAM class is nearly wide open for mods, and there are some monsterously quick cars at the national level.

DickR · Dec 19, 2017

FYI: The vast majority of the time your car will be "traction limited" in an autocross and speed limited on the street. I suggest that you save the tune money for schools, tires, and wheels until you decide you aren't really interested in autocrossing in FS. With the 10A you won't have any need for a higher rev limit and you certainly won't have any use for even more power. You might want to kept the warranty policy happy in case you get unlucky and your car has a defect (not an autocross caused problem because that isn't likely but an actual factory defect).

EFI · Dec 19, 2017

yeah F-Street doesnt allow a tune, only a narrow few select mods.

How do they verify a tune? Do they scan your computer and compare the values with a stock file before every event?

boardkat · Dec 19, 2017

EFI said:
How do they verify a tune? Do they scan your computer and compare the values with a stock file before every event?

if/when you get serious enough to start attending national events, it's very obvious to your competitors when you're competing in a large class with identical cars if your shift points differ, car gets off the line/out of digs quicker, etc. that's the first give-away. if you're bold enough to be running E85, anybody walking by your car will smell the difference. in any case, a protest will quickly follow, especially if you've put yourself high in the standings, even more so if contingencies are on the line. in my past experience observing these situations, your car will most likely end up at a ford dealership, where a factory tune will be verified. if you somehow managed to get the stock tune back on without anybody noticing (your car will be impounded and out of your possession as soon as your runs are complete), tune count can still be verified and used as a factor in the ultimate decision of innocence or guilt.

tread carefully if your mind's in the gutter, this isn't professional racing, it's racing around cones in glorified parking lots for plastic trophies. but you'd be surprised how serious some people take this shit! :lol:

DickR · Dec 19, 2017

If you do mods beyond FS you should run STP or CAM and compare your times to FS times or even a fast DS 4 cylinder Camaro or Mustang.

Mach4.6 · Dec 19, 2017

In FS you won't be able to run a H-pipe

13.10 ENGINE AND DRIVE TRAIN
C. Any part of the exhaust system beyond (downstream from) the last catalytic
converter, if so equipped, may be substituted or removed provided the
system exits the car in the original location and meets the requirements of
Section 3.3.3.B.16, Section 3.5 and Appendix I where applicable.
Modifications of any type, including additions to or removal of, the catalytic
converters, thermal reactors, or any other pollution control devices
in the exhaust system are not allowed and the system must be operable.

If you run 18" rims you'll have more tire choices also, another thing to think about
is BFG offers contingency Bridgestone doesn't

Need Some Help With Autocross Wheels and Tires

HeavyMetalMonk

Well-Known Member

Grintch

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HeavyMetalMonk

Well-Known Member

SteveW

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DickR

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NightmareMoon

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HeavyMetalMonk

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HeavyMetalMonk

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BmacIL

Enginerd

NightmareMoon

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DickR

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EFI

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boardkat

CAMtard

DickR

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Mach4.6

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