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Discussion Starter #1
FYI - I only got two autocross weekends out of a set of 255/35R18 Hoosier A6 tires on stock-size 18"x8" wheels on a G Stock Focus ST before cording the tires, so if you're looking to take a decent stab at a G Stock autocross season, budget BIG for tires. I was running 41psi using a gauge that reads 2psi lower than another gauge that I have (so it could be 43psi), and I've got frayed steel on the outside shoulder off all four tires. Two tires were used as fronts for one event, and the other two tires were used as fronts at the next event. Now, I'll be able to have these tires flipped on the rims and probably get two more weekends out of the set, but the bottom line is that the Focus ST is simply brutal on front tires. You have to spray them like a madman between runs due to rampant heat generation.

This is my 14th season of autocross and this car is by far the worst I've seen when it comes to tire life up front.
 

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I've noticed the same. Just another reason I'm thinking this car needs a limited slip differential. It should at least reduce tire wear, and improve grip at the same time.
 

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I've noticed the same. Just another reason I'm thinking this car needs a limited slip differential. It should at least reduce tire wear, and improve grip at the same time.
Agreed. Less inside wheel spin should allow the tires to last longer (and provide higher corner exit speed). Should be faster launches too with both wheels getting the same traction. Additionally, the brakes will not have to work as hard, which means they will be slightly less hot.

The believe the non-stock differential will add 5 points to the classification.
 

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The believe the non-stock differential will add 5 points to the classification.
I have no idea how the classes work, but personally, I "track" the ST everyday. I'd rather have the most possible fun in my car than potentially win more autocross events because I was conservative with upgrade choices.
 

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You've got me worried. I was planning on my tires getting me through the season.
 

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Discussion Starter #10
Hmm... I've got 26 runs on my used R6's. I will probably flip the tires before the next event too.
My car has two drivers, and I yanked the car from the competition after 29 runs due to cording. To be honest, I am not surprised to see A6s wear faster than the R6s, particularly when tire rollover is the killer in this case. The A6s grip a little more, they get hotter, they theoretically roll over more, and they will cord faster.

It's looking like the lifetime I'd expect to get out of a set of 255s on stock-size wheels in G Stock is 27 runs plus hopefully 27 more after flipping. I'm certainly wondering how much time would be lost using 225s compared to the oversized 255s. The 225s could be used to destroy the townies while the 255s could be used at the National events.

Who knows - the 225s could be faster than the 255s...but I doubt it.
 

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Would adjusting camber help?

Last year I got a set for my Mazda3 and corded the two fronts, and when I got the camber adjusted it helped it alot more
 

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Interesting but not too surprising giving the setup of the car and the size and type of tires you're running. I'd definitely be interested to see what type of difference you see with a little more appropriately sized tire for the stock size rims.

One thing I've noticed and have a suspicion of is that with the minimal feedback through the steering wheel and the super-quick ratio off-center that I'm dialing in a bit too much turn-in when pushing the car. If I end up tracking the ST I'll probably have to pay attention to this.
 

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Discussion Starter #15
Would adjusting camber help?

Last year I got a set for my Mazda3 and corded the two fronts, and when I got the camber adjusted it helped it alot more
Of course it would help, but installing camber plates in G Stock is not an option.
 

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Discussion Starter #17
Yeah, no matter what these cars are brutal on front tires. We start spraying them after two runs due to excessive heat generation, and at one event we went through 2.5 gallons of spray water and had to source some more from the pizza vendor on-site. We have sprayed the rears before but in general those are not a problem.
 

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No factory camber adjustment up front, thanks a lot Ford!

I'm hoping street tires in RTF will fare better. Less grip should equal less roll which should reduce the extreme shoulder wear on the outside front edges. But the BFG Rivals are pretty sticky, so it remains to be seen how that actually plays out. I'm afraid they are gonna require way more air pressure up front than is optimal, though, to keep from ripping the edges off of them!
 
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