Out of all the NHRA professional racing categories, Pro Stock is the most cerebral when it comes to the car. The rules that limit the class have always forced teams to be very creative and innovative with what they do at the track.
The new EFI requirements and other changes has made teams dig deep into their bag of tricks to be quick, and this includes how they deal with the spec rear tires on the factory hot rods.
We caught up with five-time NHRA Pro Stock Champion Jeg Coughlin, Jr. to get some of his knowledge and thoughts on how a team will play with their stack of tires on a race weekend. One of the important things Coughlin points out is the tracking of each tire, and how it plays into the tuning aspect of the car.
“We catalog and use the tire circumference for fine tuning the final gear ratio for finish line RPM and/or the weight and freshness of the tire for the situation. We also like to keep our tire inventory in half-inch increments. This allows us to target about a 50 RPM window per every half-inch change,” he explains.
Another thing Coughlin points out is why measuring the tires is so important when selecting a tire for a run: “The number of runs and the total circumference of the tire typically dictate the final weight of each wheel and tire. The rule of thumb is the lighter the wheel and tire combination, the less rotating weight we have to turn, hence providing for quicker acceleration off the line and in the each of the gear changes.”
Teams also consider the age of the tire, which is critical to getting down the track. “A tire that is less fresh, or has more runs on it can be more prone to spin, So, you have to pick the right conditions, like a night time run or overcast conditions, to run the aging tire,” Coughlin explains.
Check out this NHRA 101 video for more information about the art of the Pro Stock tire choice.