It looks like a slick. It...
It looks like a slick. It feels like a slick. It hooks like a slick.It must be a slick. We have news for you. It's not. It's a "ET Street" tire from the folks at Mickey Thompson. Basically, this is a specialized tire designed solely for the burgeoning Quickest Street Car marketplace. While these tires might look like slicks, there are a number of differences between the two types. Some of the differences are subtle. Some aren't.
When '55-56-57 Chevys were almost new, the hot tire setup for a fast car was a set of recapped Atlas Bucrons. Eventually tire technology evolved to the point where dedicated drag slicks were readily available. Decades after recap slicks made their debut, everything came full circle: Street tires with a tread pattern that offered the hook of a slick were developed. And with that came classes of competition where "street" tires with a tread pattern were required. The cheater slick was born. The cycle continued, and good old-fashioned slicks became the norm for almost all serious drag race applications. But then Quickest Street Car drag racing blossomed (thanks in no small part to Super Chevy Shows). Sticky street tire compounds were released. The tire wars heated up and before we knew it, tire technology had come full circle. And no, recaps aren't the hot ticket. Instead, we're blessed with what could be the most capable "cheater slicks" ever developed.
Why the fuss? That's easy. The rules for many categories of street car drag racing mandate a tire that has Department of Transportation (DOT) approval. In these categories, if you show up with slicks, you can't play. But the DOT requirement also places a heavy burden on the tire manufacturer. The company has to develop a tire that can effectively cope with an almost obscene amount of horsepower, but at the same time, it must pass a rigid set of requirements laid out by the DOT.
It doesn't take a rocket scientist...
It doesn't take a rocket scientist to see that the M/T ET Street tire has a tread pattern. Yes, it has grooves because many of the street car racing organizations mandate them. But the grooves are part of a package that is most definitely a tight rope act. As an example, M/T engineers tested a number of different groove configurations. While the actual grooving configuration and method used to develop it are proprietary, Mickey Thompson found that the groove shown here showed the best performance and overall reliability during testing. Because of this, it made the grade for the production tire.
Given the rules concoction, the "street" tires used in street car drag racing might look exactly like slicks with a couple of grooves cut in them, but they have a number of subtle and perhaps not-so-subtle differences. One factor is weight. Two issues have an influence on the overall mass of a fastest street car tire, and they're both important. The first thing one has to keep in mind is the fact a typical fastest street car is quite often heavier than it's true drag race counterpart, even if the tire sizes are identical. It's not uncommon for an "Outlaw" Pro Street racer to tip the scales at a figure that's very close to 3,000 pounds, or more. That same car can have an ultimate performance that's on par with a current NHRA Pro Stock car, but the Pro car weighs 2,350 pounds.
There's more to this weight equation: Now, it's no secret that drag slicks for unlimited applications are often constructed to be as light as possible. That just isn't the case with a tire that is forced to pass a DOT requirement. A DOT tire must have a load range (and it must have that load range cast into the side of the tire). Using the Mickey Thompson 33 x 18.5-15LT shown in the accompanying photos as an example, the overall tire weight is 43 pounds. A similarly sized conventional M/T ET Drag slick tips the scales at 37 pounds. Where does the weight come from? Mickey Thompson points out that more belt material was required in the ET Street race tire. This made for a more rigid sidewall and of course, a heavier tire. In simple terms, the manufacturer is forced to build a more robust tire if it has to conform to heavier cars and DOT requirements. M&H Tire perhaps sums it up the best: "The manufacturer must offer the right product for the weight of the vehicle. That's the manufacturer's job."
Compounding is another point that must be addressed by the manufacturer. There are a couple of different avenues taken by companies who have entered the street car drag racing arena. For example, Hoosier compounds their Quick Time Pro street tires differently than their drag tires. M&H Racemaster has developed an entire new line of compounds just for their newest "HB" series of street car drag race tires. On the other hand, Mickey Thompson uses compounds that are identical to their most popular drag slick compound (M5). Mickey Thompson supplied a compound chart to show how their ET Drag slicks and ET Street tires compare which can be found on the last page of this article.