NASCAR enforces mandatory change for ALL Cup Series teams

All NASCAR Cup series teams will have a new challenge to contend this weekend with new tires to be used for the first time.

All Cup Series teams will need to run new left and right Goodyear tires for Sunday’s Iowa Corn 350.

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The decision to debut the new tires comes on the back of a two-day test in early June at Iowa Speedway, where Kyle Bush (Chevrolet), Austin Cindric (Ford) and Chase Briscoe (Toyota) all ran to provide data from the series’ three OE manufacturers.

Why a new tire for Iowa?

Per Fox Sports NASCAR insider Bob Pockrass, the new compound comes “with the goal of more margin for carcass durability compared to what they had last year.”

Last year's race weekend in Iowa had seen multiple drivers experience problems, with five having flats in practice. Christopher Bell had to go to a backup car for the actual race after suffering a cut tire 19 laps into his Friday run.

Goodyear NASCAR product manager Rick Heinrich referenced the specific test Iowa presents for tyre manufacturers, admitting: “Iowa presents a unique challenge with the speeds and sustained loads, as well as the two different ages of asphalt on the surface.

“The new race recommendation of Goodyear Racing Eagle tires for the Cup Series is ready for that challenge, as shown during the June test.”

While Cup Series teams will run new left and right tires this weekend, the NASCAR Xfinity Series will just debut a right side compound. That was trialed by Christian Eckes (Chevrolet) and Dean Thompson (Toyota) at that test in early June.

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NASCAR tires for Iowa - facts and figures

The tires in use this weekend are as follows:

NASCAR Cup Series

Tire: Goodyear Racing Eagle

Tire Code: D-5244 left side, D-5266 right side

Previous Usage in 2025: first use (both sides)

Tire Circumference: 2,263 mm (89.1 in.) left side, 2,277 (89.6 in.) right side

Recommended Minimum Inflation: LF – 14 psi, RF – 30 psi, LR – 14 psi, RR – 28 psi

Total Dry Weather Sets: 11 (9 new race / 1 qualifying transfer to race / 1 practice)

Total Wet Weather Sets: 4

NASCAR Xfinity Series

Tire: Goodyear Racing Eagle

Tire Code: D-6106 left side, D-6134 right side

Previous Usage in 2025: Homestead-Miami, Darlington, Bristol, Rockingham, Pocono, Dover, Indianapolis (left side), first use (right side)

Tire Circumference: 2,225 mm (87.6 in.) left side, 2,250 (88.6 in.) right side

Recommended Minimum Inflation: LF – 16 psi, RF – 36 psi, LR – 16 psi, RR – 34 psi

Total Dry Weather Sets: 6 (4 new race / 1 qualifying transfer to start race / 1 practice)

Total Wet Weather Sets: 3

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