The GT Radial GT639 is a non-directional regional drive tire designed for better traction and mileage performance in regional fleet use.

The tire is made for high-mileage, high-scrub regional operations and it features a 30/32 tread depth which contributes to a longer life. It also has an open shoulder tread pattern for better traction and a wide footprint and square shoulders to improve stability.

The GT639 also has Equal Force Casing which is designed for better tire footprint and equal force distribution giving it improved control and tread wear. With the Giti Cap Base Design, the cap layer is more resistant to wear. With the cap layer's cooler running formulation, the tire is also insulated from heat buildup.

The tire also has Duo Filler Technology which is a combination of two bead fillers – hard and soft. The soft-bead filler improves comfort and handling while the hard-bead filler improves durability.

The tire comes in four sizes, 11R22.5, 295/75R22.5, 11R24.5 and 285/75R24.5. The tires have a 72-month limited warranty and a limited, two-retread casing warranty.