Barber From the Track NTT IndyCar Series Race Season

Tires to play a major role in the Honda Indy Grand Prix of Alabama

Story Credit: Jared DePouw
Photo Credit: Jared DePouw

A major part of the competition in the NTT IndyCar Series are tires. For road/street courses, Firestone Racing produces two types of slick tires: Primary (black sidewall) and Alternate (red sidewall) with the main difference between them being the hardness of the rubber. Red tires are much softer than their black counterparts, meaning logically that the reds would provide more grip than the blacks with the tradeoff that reds wear faster than blacks.

By that logic red tires are supposed to be faster, especially over just a few laps like in qualifying. However, that just isn’t the case this weekend at the Honda Indy Grand Prix of Alabama. “I felt that the car had a lot of oversteer, mainly with the red tires, which I thought we would pick up a lot of understeer” said Matheus Leist (No. 4 ABC Supply AJ Foyt Racing Chevrolet).

Typically with increased tire grip, a car will develop understeer as the stronger adhesion of the softer tires to the track reduces the overall turning ability of the car. But the opposite seems to be happening here at Barber Motorsports Park.

“As soon as the sun came out, the track got about a full second slower on the alternates” said Sebastien Bourdais (No. 18 SealMaster Honda). “That’s never been seen before.”

What’s even more puzzling about this odd situation is that both the red and black tires are the exact same compound and construction as last year. “Last year the alternate compounds used at the Honda Indy Grand Prix of Alabama were softer with more grip, which allowed for more primary-alternate gap at the pristine road course” said Cara Adams, Chief Engineer, Bridgestone Americas Motorsports. “Based on the excellent feedback received from teams and drivers following last year’s race, Firestone will bring the same race proven tires used in 2018 for the NTT IndyCar series return to Barber.”

So what could cause this sort of situation? One theory suggests that unexpected weather changes played a part. At the beginning of Friday, the track was wet from overnight rain. Throughout the day it remained mostly cloudy, but shortly before Practice 2 the sun came out. Sunshine increases the track temperature dramatically, requiring lower tire pressures than cloudy conditions. With most teams setting tire pressures long before practice starts, having too much air in a tire will decrease the amount of grip, possibly leading to oversteer.

Another factor could be the large variety of different tire manufacturers this weekend. With five different race series competing this weekend, that means there are five different tire manufacturers all laying down different rubber. Considering that not all rubber is created equally, it would make sense that each tire would react differently to other rubber. This problem is compounded by the fact that different series are on-track before each NTT IndyCar Series session.

  • Practice #1 preceded by Super Trofeo (PIRELLI)
  • Practice #2 preceded by Porsche GT3 Cup Challenge USA (YOKOHAMA)
  • Practice #3 preceded by Porsche GT3 Cup Challenge USA (YOKOHAMA)
  • Qualifying preceded by Super Trofeo (PIRELLI)
  • Final Practice preceded by F3 Americas (HANKOOK)
  • Race preceded by Super Trofeo (PIRELLI)

So how will qualifying and the race go? You’ll have to tune in to NBCSN for qualifying Saturday, April 6 at 4:00pm EDT, and the race on Sunday, April 7 at 4:00pm EDT or listen on the Advance Auto Parts INDYCAR Radio Network.

Jared DePouw
Jared is the founder of but works as a small business accountant. He also officiates high school football and lacrosse in his free time.