General Rules
Tire Approval
- – Any new tire and/or tire size(s) other than those currently approved for NTPA competition must be approved by NTPA Technical Services before being used in NTPA competition.
- Company name and/or brand along with tire size and ply rating required to be molded into sidewall of tire from manufacturer and must remain visible on any tire used in NTPA competition at all times.
- Any new tire or anytime an existing approved tire is sold to a different manufacturer or is rebranded with a different name, the tire must be submitted by manufacturer to NTPA Technical Services for approval directly from the mold before cutting.
- It is the manufacturers responsibility to submit any new or rebranded tire to NTPA Technical Services for approval before tire is cut or used in NTPA competition. Violation of this rule(s) is subject to any penalty determined appropriate by the WPI/NTPA Executive Boards.
Tire Measuring
- Tire to be measured using NTPA tools specifically designed for such purpose with tire mounted on specified rim width and inflation pressure adjusted to specifications set by tire size.
- Tread to be measured from outside to outside of tire or tread face with caliper extending outside and to bottom of any radius at outer corner of tire face or tread.
- Tire must measure less than maximum specifications for both circumference and width before being approved by NTPA Technical Services.
Mitas 24.5 Tires – (unapproved tire exception to NTPA Pulling Rules)
- Mitas 24.5 tire required to be corrected by cutting or grinding tire to maximum width of 24.5 inches in order to be used in NTPA competition. Corrected tires will be allowed in GN Pro Stock competition only. This exception to NTPA rules is limited to 60 sets maximum of inventory currently in the US as of December 2022. All tires brought to the US by Mitas from this date forward are required to be approved and meet NTPA tire dimensions out of mold before cutting. Corrected tires meeting 24.5 inch width specification will be branded with date of inspection before being allowed to compete.
Tire 48 Lug Rule
Region National classes limited to 24.5 x 32 tire with a maximum of 48 lugs are:
– Super Farm
– Light Pro Stock
– Limited Pro Stock
– Heavy Pro Stock – 5.0 turbo