confusion on tire points

[cool hand luke]

I'm looking on page 11 of the rulebook, for tire HP/weight ratio modifications and am a bit confused.

 

If I'm running a less than 9.5" non dot approved tire, what is the adjustment for this?

 

The very first line says Non DOT approved is -.75

Then the next 2 lines brake it down by size, saying 10.5-9.6 is +.4, while <9.6 is +.8

 

So would this tire combo be a total of +.05? I guess I don't know why there is the first line of -.75 that is not factored into the size categories. Seems redundant and confusing.

[kbrew8991]

It's separated out for a reason, so that non-dot narrow/wide/normal and dot approved narrow/wide/normal aren't the same correction factors but instead offers 6 different combinations. It is assumed you'll be running on a good, fresh Non-DOT slick which would be faster than a good, fresh DOT approved counterpart. It also assumes that the wider tire will be faster than the narrower tire and accounts for each of those accordingly.

 

a 9.5" or narrower slick (non-dot) would be -0.75 and +0.8 for a net of +0.05.

 

the Excel tool that was built makes doing these calculations easier, as well as illustrating some of the concepts just by clicking different combinations of the various correction factor boxes

[cool hand luke]

so what it's saying is

Non DOT > 10.5 = -.75

Non DOT <10.5 and > 9.5 = -.35

Non DOT <9.5 = +.05

Looks like I'm hitting the ballast. I can't find an excel sheet newer than 2009, anyone know where it is?

[kbrew8991]

try here:

viewtopic.php?f=2&t=39367