It's rare to come across a high-traction commercial tire that manages to live a long life. All tires are compromises, shining more in some areas than they do in others. It's one of those darned facts of life that dictate you can't have it all, yet Firestone has somehow managed to combine some qualities in the Transforce AT that would normally be considered mutually exclusive.
Picking a good tire for heavier loads can be tricky enough, and when it's a dual rear-wheel vehicle asked to perform in the dirt, things get even more complicated. Not that the Transforce is only applicable to dualies, but in this case we needed to find a tire that would hold the weight, steer well despite a narrow front tire, handle high torque loads, have decent traction in the dirt, work as well as possible in soft stuff (not exactly a dualie's fort), and ideally also last a long time. Now, that is asking an awful lot from a tire.
Rim width dictates a narrow tire with duals, making it harder for the fronts to deal with both weight carrying and steering input, plus we'd like them not to sink into anything softer than cured concrete. In the rear, the wheel spacing sets a definite limit on tire width-except in show-only applications, where bogus wheel spacers can be used to accommodate the prettiest tread pattern and sidewalls with the best tire protection absorption qualities.
Using Alcoa 16x6 wheels (rear outers only, since there wasn't enough material on the hub for centering both inner and outer aluminum wheels), we were already pushing the envelope for directional stability with a 235/85R16 on such a narrow rim. Also, while the aluminum outer wheel creates more space between the rear tires, it wasn't quite enough to satisfy the dual rear-wheel spacing specs for carrying a full load. But, as it turned out, we really lucked out with the Transforce AT.
Firestone had built these tires right, and that became obvious on the Hunter GSP 9700. Even the stock steel inner rears required just a smidgen of 3M weights, and all six tires were about as true and round as one could possibly ask for.
Initially, it seemed as if the narrow rims had compromised the steering input in tight curves, but increasing the pressure from 50 to 60 psi (running empty) cured that problem. Even at that pressure, the ride quality was very good, and the 7.1-inch-wide tread was virtually noiseless up to 50 mph. With very good traction on both dry and wet pavement, being practically immune to tracking and having low rolling resistance, plus better than expected handling, there wasn't much more to ask from the Transforce AT on the road-including when towing moderately heavy loads. Firestone had indeed met the goals of handling high torque loads and providing stability under load.
If you've ever driven a dualie in the dirt, you know it's an iffy proposition at best. Thankfully, the Transforce has enough flexibility and sufficient siping in its open tread design to pull off the practically impossible and deliver impressive traction in the dirt-even with an unladen pickup. And if somebody had said a tire this size would also work reasonably well in soft stuff, we wouldn't have believed them. Our only gripe with the Firestone Transforce AT is that when we really wished for a tire that handled this well on the road and could still get us into remote camping sites-without collecting nearly every rock along the way in the tread-and then also last a long time, the Transforce didn't exist yet.
Well, as we've mentioned in the past, tires sure have come a long way lately, getting more and more use-specific in the process. And then there's the Firestone Transforce AT, which seems to break all the rules and work great even where it rightfully shouldn't.
Tire: Firestone Transforce AT
Load range: E
Max load (lb @ psi): 3,042 @ 80
Sidewall: 2-ply polyester
Tread: 2-ply polyester, 2-ply steel, 1-ply nylon
Approved rim width (in): 6-7.5
Tread depth (in): N/A
Tread width (in): 7.1
Section width (in): 9.3
Overall diameter (in): 32
Static loaded radius (in): 14.8
Revolutions per mile: 652
Weight (lb): 41
Test vehicle: 6,100-pound Chevy V-3500