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I have been having a hard time finding a clear cut answer on what the tire limitations are in SMF class for SCCA autocross. If anyone had any insight on this it would be greatly appreciated.
Well, the SCCA rules state that "Tires compliant in Street, Street touring, or street prepared are permitted". Going off of this, I would read this as "if you can run it in those classes, you can run it in SM". 2wd STX is allowed to run up to a 265 tire, so I'd say that's the biggest you could go.
As far as compound goes, Street prepared states "The restriction that tires must be designed for highway use does not apply; purpose built DOT approved competition tires are allowed". This means you should be able to run slicks in SM.
Just a disclaimer, this is just how I'm interpreting the rules. I don't actually run SMF, I run STX.
So it sounds like pretty much as long as it is DOT I can run anything? I won't be going wider that 245 so not concerned about that. Mainly wondering if there was any restrictions on treadwear or anything.
Unless it changed in the last 2 years, you could run any DOT slick in SMF- we ran the Hankook R Comp DoT slick since it was cheaper than the hoosier.
If you do go slicks, remember to rotate them frequently to get more life out of them
Hankook Ventus Z214?
Are Toyo Proxes R888 any good?
What about Poxes RR?
So far this season ( only 4 events so far) there seems to be a common occurrence of rain. It has me debating if I should get a good all around "street" tire like Potenza RE-71R or Direzza ZII Star Spec instead of slicks. How big is the performance gap between these in the dry?
the r888 is what everybody has been using on the street lately, nothing but good reviews for those. Any R-comp will be a huge improvment over a street/summer tire.
Well, the SCCA rules state that "Tires compliant in Street, Street touring, or street prepared are permitted". Going off of this, I would read this as "if you can run it in those classes, you can run it in SM". 2wd STX is allowed to run up to a 265 tire, so I'd say that's the biggest you could go.
As far as compound goes, Street prepared states "The restriction that tires must be designed for highway use does not apply; purpose built DOT approved competition tires are allowed". This means you should be able to run slicks in SM.
Just a disclaimer, this is just how I'm interpreting the rules. I don't actually run SMF, I run STX.
Width is more or less unregulated in the Street category. STX puts a limit on width and UTQG, but since it's unregulated in Street Prepared it's also allowed in Street Modified. Formatting and emphasis is mine.
Originally Posted by SCCA Solo Rules
Street Tire rule section
Tires may be replaced with any size that fit the allowable wheels and fender wells without modification. (section continues to list minimum production size, treadwear, and other specifications not particularly interesting)
Originally Posted by SCCA Solo Rules
Street Prepared tire rule section 15.3
Tires must meet the requirements for Street Category with the exception of Sections:
13.3.A.1 (minimum UTQG Treadwear Grade) Allowing any treadwear.
13.3.A.2 (minimum molded tread depth) Allowing any tread depth.
13.3.A.5 (must be designed for highway use) Allowing offroad/track purpose built tires
Huh, must have missed that part of the SP tire section. So I guess you can use as big a tire as you can squeeze in there. From what I've witnessed, there is a MASSIVE difference between slicks and 200tw tires. I run 255 RE-71R's, and they have tons of grip in the dry, but I haven't tried them in the wet. From what I understand, if you run a class that allows slicks and don't run them, you will not be competitive with those that are.
07-31-2016 | 08:17 PM
