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Magus2727

Clarification of rules for TT/ST6

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Magus2727

 Sorry if these are newbie questions.

1.  Under 6.1.2 - 1).3 is says DOT-approved R-compound autocross tires (“A-tires”) are not permitted in ST5 and ST6.”  Is there a way to tell a difference in autocross tires?  Specifically I am looking at the RC-1's.  They are a 100 UTQG rating (so would get an advantage of the modification factor of +0.5) but on Maxxis site it specifically says "DOT-approved R-compound" but does not say autocross. 

2.  6.1.3 - 2.)3 says removal of plastic wheel well liners is fine.  If the OEM liner is a fabric does it that allso allow?  I have plastic front liners but in the rear its a fabric. 

3. 6.1.8 - Talks about transmission limitations.  It does not talk about differentials and the install of limited slip differentials.  Searching of the document I found it does not talk about differentials at all and the install of helical or disc/clutch LSD's.  Are these allowed to be installed with any limitations or restrictions in TT/ST6? 

4.  Measure of track width.  In my searching it looks like industry sets track width from center of tire to center of tire.  This type of measurement does not take into account the bulge of the tire sidewall (but don’t think that really matters?).  My weight I am allowed a 30mm bulge.  When calculating and measuring track width to make sure I comply to the less than 4" of increase in track width which is the proper way to measure?   Measure outside bulge of one side tire to inside bulge to the next tire? 

 

Thanks!!!

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Clavette

1.  RC-1's are allowed.  A tires are specifically called out A7's, Z214, and one other I can't recall.

4.  NASA makes a tool.  It also provides a template for you to make the tool to test your tires.  It's simple...if it fits, the tire passes.  If it doesn't, the the tire fails.  Use the tool.

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Magus2727
49 minutes ago, Clavette said:

1.  RC-1's are allowed.  A tires are specifically called out A7's, Z214, and one other I can't recall.

4.  NASA makes a tool.  It also provides a template for you to make the tool to test your tires.  It's simple...if it fits, the tire passes.  If it doesn't, the the tire fails.  Use the tool.

For #4 that tool is for the tire width, not track width.   It looks like most will either measure outside of tire to inside of the next tire.  Or measure the whole width outside to outside and subtract a wheel width since they have the measurement tools and most people are likely going to be close to the 266/257/226 tire widths.   

for #1 wanted to make sure and after more searching it looks like people call it out and found the fit guide.  looks like the 255/40R176 fits the 257mm width tool when installed on a 9" wide wheel.  

 

Thank you for your comments. 

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Clavette
4 minutes ago, Magus2727 said:

For #4 that tool is for the tire width, not track width.   It looks like most will either measure outside of tire to inside of the next tire.  Or measure the whole width outside to outside and subtract a wheel width since they have the measurement tools and most people are likely going to be close to the 266/257/226 tire widths.   

for #1 wanted to make sure and after more searching it looks like people call it out and found the fit guide.  looks like the 255/40R176 fits the 257mm width tool when installed on a 9" wide wheel.  

 

Thank you for your comments. 

 

I never came across the bulge question myself.  I run in TT3 and have only had to demonstrate compliance with the tool.  Make sure to post what you learn.

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