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I would like to start by saying I have read every single post in this thread, as well as searched the forum as best as I could.

I just purchased a 2016 ST1 with the intention of daily/autocross use.

I am 100% lost when it comes to tire and wheel measurements. If someone would be so kind to be painfully clear to me I would really appreciate it.

Right now I have in my Tirerack "cart" the:

O.Z.
ULTRALEGGERA
17x8
Finish: Black Painted

AND

BRIDGESTONE
POTENZA RE-71R
245/45R17
Sidewall Style: Blackwall
Serv. Desc: 95W

This is based off what I have seen on setups in this thread as well as others.

My main question is this a legal setup? If so is this my best bet? Would I be better off going with a 255 tire? Is 245/45 the correct size? Or do I want 245/40? (not 100% clear on what the 2nd number means)

I appreciate any help and insight. My intention is to stay in GS with this tire/wheel setup, break pads, and high temp fluid.

Im excited to hear some feedback and look forward to learning more about my ST.

Thanks guys
 

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I would like to start by saying I have read every single post in this thread, as well as searched the forum as best as I could.

I just purchased a 2016 ST1 with the intention of daily/autocross use.

I am 100% lost when it comes to tire and wheel measurements. If someone would be so kind to be painfully clear to me I would really appreciate it.

Right now I have in my Tirerack "cart" the:

O.Z.
ULTRALEGGERA
17x8
Finish: Black Painted

AND

BRIDGESTONE
POTENZA RE-71R
245/45R17
Sidewall Style: Blackwall
Serv. Desc: 95W

This is based off what I have seen on setups in this thread as well as others.

My main question is this a legal setup? If so is this my best bet? Would I be better off going with a 255 tire? Is 245/45 the correct size? Or do I want 245/40? (not 100% clear on what the 2nd number means)

I appreciate any help and insight. My intention is to stay in GS with this tire/wheel setup, break pads, and high temp fluid.

Im excited to hear some feedback and look forward to learning more about my ST.

Thanks guys

Welcome. GS is a bunch of fun and a real driver's class. You can make little tweaks to the car and improve the response/feedback some, but the ST's are really good out of the box.

As others have said, you want the 255/40/17 or 245/40/17 instead of the 245/45/17. The second # (aspect ratio) corresponds to the sidewall height. The 40 or 45 in this case tells you how tall the sidewall is as a percentage of the tire width. Ex: the 255/40/17 has a sidewall height of 255x.4 = 102mm. In contrast, the 245/45 has a sidewall height of ~110mm. In this case, that will both raise the height of the car by 10mm and make the steering feedback slightly worse. The 245/40/17 is not much different from the 255/40/17 when you put it on the same 17x8 rim. I've run both. The 245/40 feels a tiny bit different, but I haven't found a distinguishable difference in the times they can produce.

The OZ's are a nice wheel and class legal. If you go OZ, make sure you get the +55 mm offset ones. +45mm offset is not GS legal (+/- 7mm from the stock 55mm offset) You can save some money and run the 17x8 Moda (must be 48mm offset model) wheels instead. I run the MD18 style.

The only other change most folks make is a rear bar. Most everyone goes away from the stock bar due to the designed-in bushing bind that leads to very abrupt rear break-away (oversteer) characteristics. Some like a smaller bar (stranoparts) while others prefer larger (cobb or others). IMO, it's more driving style and situation dependent than one bar being clearly faster than the others. Some change rear end links as well. Depending on which bar you run, adjustable endlinks might be better. I'd steer clear of the steeda ones. I did not like how they fit with the strano bar nor their attachment design.

I run the stock brake pads and stock fluid, but don't typically have a co-driver. I've been at events where ST's have had the brakes overheat with two drivers and high temp fluid. (Ask BA89 for more details)
 

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I run the stock brake pads and stock fluid, but don't typically have a co-driver. I've been at events where ST's have had the brakes overheat with two drivers and high temp fluid. (Ask BA89 for more details)

With two drivers at an event last year at Toledo Express airport we boiled the brakes after 4 runs. This was with Hawk DTC-30 pads and OEM fluid. Bleed the brakes and a ton of air came out. Switched to Stoptech STR600 fluid, bleed regularly, and have never had an issue sense.
 

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Edited for rear tire pressure which makes a massive difference

Late to the thread but adding mostly to share tire pressures. I worked down from 38F/38R to 35F/30R by chalking and 35F is very close to the sidewall and 30R is not as close but feels good. Lots of people running high rear pressures for rotation but this setup rotates pretty well. I seem to be killing the tires though, I am seeing roughness and pulling at corners in the tread.

2015 Focus ST3 w/sunroof

Wheels: Sport Edition A15 17x8 et48
Tires: Bridgestone RE-71R 255/40/17
Pressures: 35F 38R (was 30R)
Sway Bar: Stock
Sway Bar End Links: Stock
Shocks/Struts: Stock
Exhaust: Stock
Brake Pads: Stock
Brake Fluid: Stock
Oil: Mobil 1
Air Filter: Green Filter With Cap
Alignment: whatever came from the factory
 

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Fun first post for me here. Been lurking long enough and I actually have a FoST now.


YR/Model: 2016 ST3 --- No Sunroof though
Wheels: 17x8 Enkei RPF1 Finally available in the GS size
Tires: Bridgestone RE-71R 255/40-17
Pressures: 38-35f/30-32r Depending on rear
Sway Bar: Rear Fswerks 25mm on soft (going to try this out before I switch to a stranobar)
Sway Bar End Links: Stock (For now)
Shocks/Struts: Stock (Will have OTS rear konis this year)
Exhaust: Stock (For now)
Brake Pads: HPS
Brake Fluid: Stock
Oil: Stock
Air filter: Stock
Alignment: Getting done next week, going to get as much camber as I can and going to pay around with the toe


Also I like skittles and cupcakes.
 

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Fun first post for me here. Been lurking long enough and I actually have a FoST now.


YR/Model: 2016 ST3 --- No Sunroof though
Wheels: 17x8 Enkei RPF1 Finally available in the GS size
Tires: Bridgestone RE-71R 255/40-17
Pressures: 38-35f/30-32r Depending on rear
Sway Bar: Rear Fswerks 25mm on soft (going to try this out before I switch to a stranobar)
Sway Bar End Links: Stock (For now)
Shocks/Struts: Stock (Will have OTS rear konis this year)
Exhaust: Stock (For now)
Brake Pads: HPS
Brake Fluid: Stock
Oil: Stock
Air filter: Stock
Alignment: Getting done next week, going to get as much camber as I can and going to pay around with the toe


Also I like skittles and cupcakes.


Pictures? I really want these wheels. They claim 15.8lbs.... REALLY!? is it true?
 

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Pictures? I really want these wheels. They claim 15.8lbs.... REALLY!? is it true?
When you can carry around 2 almost as easy as you can carry ONE stocker #racecar
 

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YR/Model: 2013 ST2 (With ST3 Seats)
Wheels: 17x8 Enkei RPF1 (black)
Tires: BF Goodrich Rival S 1.5 255/40/17
Pressures: 38F - 32R Give or take
Sway Bar: Strano Rear
Sway Bar End Links: Stock
Shocks/Struts: Stock
Exhaust: Roush
Brake Pads: stock
Brake Fluid: Stock
Oil: Stock
Air filter: green w/cap
Alignment: street/stock

Someone asked for a picture with said wheels on the car so I figured I would provide a snap.
my car.jpg
 

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YR/Model: 2013 ST2 (With ST3 Seats)
Wheels: 17x8 Enkei RPF1 (black)
Tires: BF Goodrich Rival S 1.5 255/40/17
Pressures: 38F - 32R Give or take
Sway Bar: Strano Rear
Sway Bar End Links: Stock
Shocks/Struts: Stock
Exhaust: Roush
Brake Pads: stock
Brake Fluid: Stock
Oil: Stock
Air filter: green w/cap
Alignment: street/stock

Someone asked for a picture with said wheels on the car so I figured I would provide a snap.
View attachment 237473
54 GS is the same number I use for autocross on my 2013 TS ST2. Wheels look great on your car!
 

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YR/Model: 2013 ST2 (With ST3 Seats)
Wheels: 17x8 Enkei RPF1 (black)
Tires: BF Goodrich Rival S 1.5 255/40/17
Pressures: 38F - 32R Give or take
Sway Bar: Strano Rear
Sway Bar End Links: Stock
Shocks/Struts: Stock
Exhaust: Roush
Brake Pads: stock
Brake Fluid: Stock
Oil: Stock
Air filter: green w/cap
Alignment: street/stock

Someone asked for a picture with said wheels on the car so I figured I would provide a snap.
View attachment 237473
Thanks for the picture! is it night and day difference on wheel weight?
 

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They are very.....VERY....light wheels, and they are excellently made obviously. They are lighter even than the OZ wheels that were the "best" option for the class for the longest time now, and they are cheaper by a fairly meaningful margin.

One thing many people fail to discuss about the "common" tire set up is that these 255 tires are very heavy, so having the lightest wheel possible is pretty great. As we know unsprung weight is pretty much the devil, so the lighter the better. Also i can tell you there is just something about RPF1's that make a man feel good, they are a no nonsense high quality wheel, and I highly recommend them.
 

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They are very.....VERY....light wheels, and they are excellently made obviously. They are lighter even than the OZ wheels that were the "best" option for the class for the longest time now, and they are cheaper by a fairly meaningful margin.

One thing many people fail to discuss about the "common" tire set up is that these 255 tires are very heavy, so having the lightest wheel possible is pretty great. As we know unsprung weight is pretty much the devil, so the lighter the better. Also i can tell you there is just something about RPF1's that make a man feel good, they are a no nonsense high quality wheel, and I highly recommend them.
Thanks for sharing your thoughts.

if you might be able to weigh a "stock snowflake with stock size tire" vs "RPF1 and tire"

Thanks
 

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Sorry I haven't posted a picture. I was hoping someone would have had one from our event last weekend. The car worked pretty damn well and I finished 8th overall on PAX which for our local I will take as there are a lot of national trophy winners around.

AXti.me Event Results: 2017 MAC #02

You can feel the weight of the tires so I am glad that I got the RPF1s. The car rotates very well, which is good.
 
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