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front tire width max?

PeteInCT

#LS-378 - So many Porsche's, so little time....
Moderator
2,848
14
Connecticut
285's fit, but larger than that you may have a problem with the brake cooling ducts and need a different offset wheel or spacers. As far as the inside of the wheel well, there a lot of room as long as you have stock suspension.
 
To be honest with you i was thinking about putting my back wheels up front and steal my GT500 back tires and put them on the back haha. Its my first race if i do well ill invest in new tires and wheels.
 
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Dont know if this is for aesthetics or function, but Vorshlag utilizes a 11" wide Forgestar F14 wheel and 315 tires on their 2011 Brembo GT. It sticks out a fair bit, and is meant for auto-cross functionality. Dont know if they could have done it with stock dampers though, or any other struts on the market, as they use AST4100 coil-overs.
 

zzyzx

Steve
299
0
For stock class autox, you're limited to the stock wheels which are the limiting factor.

I'm in a similar situation now, running in the RTR class, on 275/40F, 295/35R PSSs.

On the stock wheels, at least 285F, 305R but that depends on the tires - in stock you'd be running R comps and Hoosiers tend to run big.
 
In previous conversations with others on the forum board I believe they said you could run 305's on all four corners. I too am looking this spring to go wider on all 4 corners using the stock rims if possible......but not sure what I can do yet.

If anyone has done so or tried out various sizes on the stock rims please let us know. Thanks in advance!
 
jfolsom28 said:
What is the biggest tire you think you can fit under the front without modification trying to get into autocross for stock class.

If you’re planning to run SCCA Autox in Stock class you must run a stock size wheel with the only change being you can change the backspacing/offset by 1/4 inch. Wheel size must be 19x9 up front and 19x9.5 out back as per the SCCA rules as that is the stock wheel size for a Boss 302. As for tires, anything bigger than a 275 on the 9inch front will do more harm than good. Oversize tires on the rim usually cause the tire to roll over which actually decreases grip. On the back a 285 is about as big as I would recommend for the same reason. Yes you could increase tire pressure to limit role over, but that limits grip as well. My recommendation is to run a 275 all the way around that way you can swap the tires front to back halfway through the season. Bottom line in Stock class the factory wheel size is the limiting factor, not how big a tire will fit in the wheel well. There are other opinions I'm sure, but that is what I recommend. I decided to run the Boss in STX this season which opens up a whole list is problems as rim width is limited to 9 inches, but any rim diameter may be used. Also the PAX is lower so it should payoff, which is did in 2012 as I won the class in a 2010 Mustang GT with only a 245x40x18. I’m running 18x9s with 265x40x18’s RS3s this season on the Boss. Good luck with your tire choice.
 
F-Stock Shelby Mustangs run 295/30/18- A6 Hoosiers on an 8.5" wheel.

295 front/315 rear on a 9"/9.5" wheel (Boss size) will be the best combo. Don't be fooled with rolling over (adjust with air pressure). Be more conscience of how many runs you get out of the fronts with limited camber adjustment. Normally the issue in stock classes.

You get the choice of changing your front or rear bar. Bigger front bar will increase front roll stiffness, response, and tire wear, but might induce more understeer during mid corner and exit. Stiffening the rear will help steady state, slalom, and general rotation, but might hurt putting power down at exit. Make sure the bar is adjustable which ever you decide. If I was in AS instead of ESP, I'd opt for the rear bar. You should be able to exit fairly well with 315's. A set of AST's with the correct lower spring perch wouldn't hurt either.

Call Strano as he has an abundance of bars to choose from, front or rear (plus some multi F-Stock National Champion, S197 advice).

Dave
 
My experience has been a correctly sized tire has produced the best results and longest tire life. There are definitely other choices. I agree that Sam Strano knows how to make a S197 go fast. I've purchased parts from Sam and listen to his advice for many years now. I just choose a different route when it comes to tires sizes.

Chris
 

zzyzx

Steve
299
0
I think Dave nailed it. If you've had the opportunity to frequent Solo Nationals, you'll note that all those excessively wide tires on the stock wheels are not there for decoration; they're there to eek out that last 0.001 sec per run.
 
zzyzx said:
I think Dave nailed it. If you've had the opportunity to frequent Solo Nationals, you'll note that all those excessively wide tires on the stock wheels are not there for decoration; they're there to eek out that last 0.001 sec per run.

Steve,

I haven't seen you at Nat's in a while, where ya been? Still supporting the Sti/Evo crowd?

Dave
 

zzyzx

Steve
299
0
iDrive said:
Steve,

I haven't seen you at Nat's in a while, where ya been? Still supporting the Sti/Evo crowd?

Dave

Hey Dave!

Good to see you here! It seems we share something in common. I'm now in south FL, so I'm not conveniently located to Solo Nats anymore. I "took a break" from building suspensions for the STi/Evo crowd for the past few years. Enjoyed it for the many years I did it, though. I miss building stuff stuff in the machine shop, truth be told.
 

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