TT Calculator

NOTE:  The formulas for our TT Calculator have been revised for the 2019 season, be sure to run your vehicle through it again as it may be classed differently than when it was first implemented in 2018.

This is our simple TT classing calculator we started testing the last half of 2018.  Make sure to answer all the questions to determine your class for our Gripfest events.  This was designed as a constant work in progress meant to improve upon the old classing system (street tires or race tires, and that was it) in an attempt to provide some parity between vastly different vehicles. If you have any questions about your classing, or you have a unique vehicle that you believe cannot/is not accurately classed by the system (such as a Tesla or an S10 X-treme) please email

Please give it a minute or so to load – when multiple people are using it at once it can slow down.

Classes “A” (faster) through “F” (slower) are for all production cars – any tube chassis, home built/kit cars go straight to our Unlimited “U” class. Production cars with a high enough points/modification level can get bumped into “U” class.

Example: a C7 Z06 with the factory aero and R-compound tires starts out in “A”, but with exhaust modifications(other than a cat-back) gets bumped to “U”.  Cars that must run in “U” class regardless include Factory Five 818, Exomotive Exocets, all Formula cars, etc. Email if there are any questions.  For now the Factory Five Cobra replicas will be considered production based but must take the hit for Stripped Interior by default.

You may opt to run in a faster class by choice, but not a lower one.

Example: If your car qualifies for “E” class, then you may choose to run “D”, but not “F”.