Mickey Thompson’s ET Street and ET Street Radial II tires are among the elite high performance street meats on the market, delivering unparalleled performance on the drag strip while maintaining streetability with a D.O.T.-approved design, giving you essentially the best of both worlds in one package.
The two tires differ in their tread and sidewall design, and carry minutely different measurements, thus delivering added advantages over the other depending on the type of driving you’re doing, the vehicle combination, and your needs on the street. To better quantify this, we set out to compare and contrast the two tires, using our turbocharged 2011 Ford Mustang Project Wild E. Coyote as the test mule, to see how the two siblings measure up to one another at the track and on the freeway. In doing so we’ll take an in-depth look at the two tires, their construction make-up, and compare sixty-foot and quarter-mile numbers, as well as the overall ride and handling characteristics, to get a better grasp for these two workhorses, all with the expert input of our friend Tom Kundrik at Mickey Thompson.
Our two subjects: the 28 x 12.5/15LT ET Street on the left, and the P305/35R19 ET Street Radial II on the right.
The ET Street
Mickey Thompson’s ET Street tire is among the highest-performing D.O.T. class race tires on the market, with a bias ply construction that borrows many of the structural attributes of the company’s ET Drag slick race tire, making this a potent tire that can plant the horsepower to the ground, while delivering a worthy and reliable ride on the road, as well.
The ET Street is a wrinkle sidewall type of tire, just like a slick, with a design that typically uses nylon or polyester ply cords that are run at a 45-degree angle to the tires’ bead. The cords criss-cross in an overlapping pattern, which forms a thick layer that’s less flexible than a radial. Because the crown and the sidewalls are interdependent, the sidewall flex in a bias tire is transmitted to the tread, which allows it to ‘squat’ on the starting line.
The venerable ET Street is built upon a bias play design, much like a drag slick, which means it has a soft, wrinkle sidewall that allows it to absorb energy upon launch and plant the power to the ground.
“With its bias ply construction, the ET Street is generally more forgiving with stick shift vehicles, and will be more compatible with the Mustang that you’ll be testing the tires, on,” says Kundrik.
The ET Street Radial II
“When the ET Street Radial II was originally designed, it was intended for mostly street-driven vehicles, that would go to the track here and there,” says Kundrik. “It was created with a performance compound on it to help get traction, but still perform decent in the wet conditions on the road. We don’t recommend driving the tire in the rain, because it’s really more of a race tire.”
You can see the differences in the sidewall depth between the two tires, with the ET Street Radial II — a radial ply-design tire, in the foreground. While absorbing less energy on the starting line, the stiffer design makes the Street Radial II inherently more at-home on the road then the ET Street.
The Street Radial II, as the name implies, rests on a radial tire design, in which the cord inside the tire is positioned at a 90-degree angle from the bead, which makes it better conform to the surface of the road. With a radial, the sidewall and the tread are fully independent of one another, and thus, the sidewall flex is not transmitted to the tread.
As Kundrik points out, this design is meant to be less forgiving, but faster if you can make them hook up and go on the starting line, as they have less overall rolling resistance once they get rolling. However, the radial tire doesn’t grow at speed like a bias ply-type tire does.
How do They Differ?
On the stick shift car, a bias ply tire is always going to be better, because it absorbs power. When you dump the clutch, the tire absorbing the power is what you want so that it can hook. – Tom Kundrik
As Kundrik put it in simple terms, the ET Street Radial II is meant more for street driving and occasional track use, whereas the ET Street is intended more for street and strip purposes, with a slant toward more racing use — your ‘weekend warrior’ types, if you will — that goes to the track regularly and beats on their cars.
“On the stick shift car, a bias ply tire is always going to be better, because it absorbs power. When you dump the clutch, the tire absorbing the power is what you want so that it can hook. The radial tire likes to be loaded, and then kept loaded, so at the hit when you drop clutch, the radial doesn’t like that initial shock — it’s more catered to smooth power development. At the 1-2 shift is where they will literally knock the tire off, just because it likes to be kept loaded,” Kundrik explains.
In comparison, a bias-ply slick tire absorbs the power and then un-springs it, making it a more forgiving tire for a stick shift vehicle, as Kundrik pointed out to us.
Both the ET Street and ET Street Radial II carry D.O.T. stamping, and while the similarities stop at their very different construction, these two tires aren't so different. They excel at two different things, but they still perform very well, whether on the street or the strip.
As far as overall performance, Kundrik told us, “If both of the tires hook up, the ET Street probably won’t be as fast, because a radial is inherently faster than a bias ply tire is, but the ET Street will perform well on the starting line, because it can wrinkle the sidewall and absorb the energy.”
This is a point that Kundrik told us Mickey Thompson’s engineers are quickly closing the gap on, as they press on to uncap new potential in radial tire technology, allowing them to perform as well as their bias-ply and slick tire counterparts while still delivering a near road-tire feel. This is never more evident than in the numbers that have been laid down with their world-beating new ET Street Radial Pro tire, which has propelled doorslammers deep into the four-second range with sixty-foot clockings as quick as 1.05-seconds.
“We’re learning more about the radial tires and we’re closing the gap on making a radial tire perform as good or better than a bias tire. It’s coming,” Kundrik states.
In terms of air pressure at the drag strip, Kundrik shared that radials generally demand higher pressure than a bias tire, with the bias tires often in the 14-15 psi range and the radial between 16 and 20. As well, he says with the larger 19 and 20-inch ET Street Radial II’s, because they have such a much shallow sidewall, they need less air pressure than a radial tire of smaller diameter would normally necessitate.
ET Street: Tube Or Tubeless?
The ET Street tire lineup — with the exception of the 17-inch — can be run with a tube inside rather than the standard liner that’s present in the other models. Because a bias tire is porous, the tube can be utilized simply for air retention, to keep one from needing to air the tire up more often. But on the track, the tube can improve reaction times and reduce sidewall shock and deflection upon launch, allowing the tire to return to ‘round’ quicker.
Our Experiences – By The Numbers
The results of our real-world tire comparison really illustrated the differences that we’ve highlighted here between the ET Street and ET Street Radial II, and that’s particularly the case given our combination. Wild E. Coyote is a stick-shift car, with an RGR-built 5.0-liter Coyote powerplant paired with a JPC turbo kit making more than 600 rear wheel horsepower on a conservative 8.5 pounds of boost, so we really gave each set of tires a workout.
The need to hit the tires hard on a stick car is magnified with the use of a turbocharger, and we saw that play out in how we had to go about launching the car when running on the ET Street Radial II. With that tire, we’d rev the engine to 4,000 rpm in the beams, and then quickly clutch the car out to make it hook at the initial hit. With the ET Street, we could vary the two-step on the launch from 4,200 to 4,800 rpm, depending on track conditions, and just dump the clutch. At this point, it would be build 2-3.5 pounds of boost initially and hook, allowing us to sixty-foot considerably quicker.
As a caveat to our testing, the two tires were run on two different race weekends, and while running the ET Street Radial II’s, we were producing two more pounds of boost on a race gas tune, then when we were on the ET Streets, which clearly translated into quicker elapsed times and higher trap speeds overall. But as you can see, we produced much quicker sixty-foot clockings with the ET Street while making less horsepower, simply because of how well the tire performed with our stick-shift combo right out of the hole.
Wild E Coyote on the track, running the ET Street (left) and the ET Street Radial II (right).
We carded a best quarter-mile run of 11.15 at 130.95 miles per hour on the ET Street Radial II at the Auto Club Dragway in Fontana, with a best short time of 1.81 on our two example runs. With the ET Street, we weren’t as quick or fast, turning only an 11.32 best at 120.71, but as you can see, we were 1.67 and 1.71 to the sixty — not only quicker by a tenth, but also more consistent than with the ET Street Radial II. Taking the variables into account, there’s no doubt with the roles reversed, the ET Street would have pushed us well into the 10’s.
We tested the two tires on two different race weekends with a considerable difference in boost (and therefore horsepower on tap), but even with less grunt, the ET Street still outperformed the ET Street Radial II in sixty-feet, and were the roles reversed, would certainly give us 10-second elapsed times.
On the Street
Our street driving experiences also went as expected, as the ET Street Radial II, with it’s radial tire design and stiffer sidewall, really performed and felt just like your typical street performance tire — able to take corners and even evasive action at speed with excellent response. The ET Street, meanwhile, exhibited some of the “slosh” you might expect from a wrinkle sidewall tire during normal driving conditions. This is partially attributed to the soft sidewall and to the lower tire pressures the tire must be run at, but simply illustrates the differences between the two tires and where the tradeoffs exist between them.
Project Wild E Coyote, sporting the ET Street’s at the track.
With two tires of this caliber, there really isn’t a “bad” or “wrong” choice. As our look at these tires pointed out and our testing confirmed, each has been designed to do two different things, with some pros and cons to each. Both are plenty capable tires, and with D.O.T. stamping, each will get the job done, but it really comes down to your needs and your driving and use tendencies. If you consider yourself a track warrior and you do very little driving in mostly dry conditions, the ET Street will give you a little performance edge on the quarter-mile. But if you do a good bit of commuting and still want a tire that can hang at the track, the ET Street Radial II is the answer.