Four-link dragsters benefit...
Four-link dragsters benefit from a 16 x 33-inch tire like this Goodyear Eagle, because it's so big. Check with your specific tire dealer on which compound to use. Compounds are listed in the accompanying story here.
Like cams, carbs, and chassis settings, selecting the right "shoes" for your machine can make the difference between winning and being an also-ran. More than once we've heard the phrase, "Tires win races." Okay, fine. But which tire is best? That is an age-old racing question. Maybe we can help.
We talked to representatives from Firestone, BFGoodyear Hoosier, Mickey Thompson, and Goodrich to find out how they help match up their customers' racing machines with the best tire for their combination. Our goal is to lay out their advice in a format that will at least get you into the ballpark when selecting the rubber for your ride, focusing on helping you select the right size, compound, and type of tire for your vehicle.
Although it doesn't sound easy at first, once you set about selection in a methodical manner, the right one for you is not hard to find. The goal is to select a tire that allows your car to hook the same every time, preferably without tire spin, leading to consistent 60-foot times on every pass.
A pair of dragsters burn out...
A pair of dragsters burn out on their massive drag slicks. The Goodyear slicks on the car in the foreground were made specifically for this fast bracket car. A good burnout is essential.
First, you need to decide how you intend to use the tires. If you drive your car to the track, are you going to change to performance tires, or do you intend to drive to and from the track on them? Using the same tires to drive home on definitely limits your choices. BFGoodrich makes a number of sizes of their Comp T/A Drag Radial, a tire that is an honest-to-goodness street tire, although the tread will wear out relatively quickly. However, the same things that make them a good street tire-sidewall stiffness, for example-limit their effectiveness on the track for cars with any kind of serious torque.
Mickey Thompson's Sportsman Series tires also work okay on the street, but the sidewalls are still not flexible enough to hook well with high-torque applications. Face it, any tire that works in both environments has to make serious compromises. While M&H Racemasters, the new M/T ET Street or Hoosier Quick Time Pro tires may be DOT-approved and are legal for DOT classes, they'll scare the heck out of you off the track, not to mention the fact that the manufacturers tell you not to use them on the street. Save these for the track.
BFGoodrich doesn't make "slick" slicks, but the company does make a wide variety of D.O.T.-type racing tires that hook up just as good as a regular slick. Its line of Comp T/A Drag Radials comes in so many sizes-we counted 13-that the D.O.T. racer won't have a problem choosing which "feet" to wear on the drag strip.
Here's a Hoosier DOT-approved...
Here's a Hoosier DOT-approved drag slick that can be used for DOT-class cars that mandate a tread. The tire is still "slick"-soft.
Downloading info from BFGoodrich's web site, www.eurotire.com/goodrich
, we found tires that ranged from an overall diameter of 24.2 inches and a tread width of 6.9 inches to its biggest, a 29.9 incher that had a tread width of 12 inches. The tires are especially attractive to the guy who wants to put a pair of good-hooking tires on his car without having to go through the hassle of installing tire screws in the rims, because according to BFGoodrich's literature, none are needed. Sizes range from P215/60R14 to P315/35R17. Each tire in Goodrich's racing catalog is "R," for radial, rated.
Are there any tire restrictions in the class you will enter? Obviously, a drag slick is unwelcome in Trophy or DOT tire class. Feron Lubbers of Hoosier pointed out that those racers might want to consider a Quick Time Pro tire. They come with a medium soft D05 compound, identical construction to their slicks, they have a couple of grooves in them, and they qualify as a DOT tire.
M/T ET Street tires are basically the same as an M/T ET Drag slick also, but are DOT-legal. Classes with a 10.5-inch tire limit make choices a little easier. Just pick your favorite brand.
Sometimes the width number doesn't always correspond with tread width, like tires with a "W" suffix on the part number. Several years ago, fellow racer Chuck Conaway gave us some well-worn 6-inch Firestone "W" slicks that actually measured 8 inches wide. To deal with that, some organizations like Hot Rod, PHR, NMCA, and NSCA supply a go/no-go gauge. If the tire's too wide, you don't pass tech. Simple.
Another popular Mickey Thompson...
Another popular Mickey Thompson tire is this "E.T. Street" slick used in many DOT-type applications. We've found that there's not much difference in ETs from regular slicks and this type tire.
Another limiting factor may be the wheels you have. The tire reps said to keep the tread width within plus or minus 1 inch of the rim width, but a look at Goodyear's Web page shows they actually allow a little bit more tolerance. The Hoosier catalog actually recommended an 8.5-inch wheel for their 10-inch slicks, but also said the 10-inch wheel was fine.
How big are your wheelwells? Sometimes your car is the limitation. Novas are notorious for not allowing anything wider than 9 inches, although I have seen 28 x 10 Goodyears under the stock wheelwells of one. And I've even seen leaf springs trimmed to clear the tire, a practice that doesn't sound too safe, but appeared to function.
What is your rearend gear ratio? Mickey Thompson representative Jerry Francis said they recommend most cars with a three-series gear ratio like a 3.27:1 use a 26-inch-tall tire. If your machine uses a four-series gear, go up to 28 inches. Past that, you need to do some talking with the representative, but definitely go with a taller diameter, which gives a bigger footprint.
Francis also noted that any tire can be overpowered. "If you put a 26-inch slick under a heavy car with a 3.73 gear and a big nitrous kit, you will see tire spin," he says. Although some of the 10-inch tire guys hit the eight-second range in the quarter mile, you can safely bet money they spin just a bit. Francis noted that in the smaller tires, generally up to 29-inches tall, compound selection is not even an issue. He said there is usually only one choice, a medium-soft compound.
Mickey Thompson Performance...
Mickey Thompson Performance Tires makes this 28 x 10.5 x 15-inch slick for bracket racers who are somewhat limited by wheelwell space. It's one of the company's "ETDrag" slicks.
Goodyear calls their medium-soft a D3, Firestone says theirs is the F9 series, Hoosier's is D05, and Mickey Thompson L8. These compounds work well with many combinations, our tire men say. Obviously, when one gets into faster cars, compound selection becomes more crucial. Firestone representative and Super Stock racer Mike Crutchfield says that one of their rules of thumb for selecting compounds is, if your race car is under 2,500 pounds, use a soft compound, and anything over should use a medium compound.
Firestone's main compounds are F9, a medium-soft compound, and F30, a soft compound. Hoosier makes a D05 (medium-soft), and a D07 (soft). Goodyear's most popular compounds are D3 (medium), and D5 (soft). Mickey Thompson's medium compound is L8. All the manufacturers also offer other compounds designed for specific applications. Goodyear rep Eric Rang pointed out that Goodyear offers nine different compounds, each having a specific application, in this order, from softest to hardest: D-1, D-2, D-12, D-9, D-6, D-5, D-7, D-3 and D-10. If your car can run either soft or medium compound tires, ask yourself which is more important to you: Better hook and shorter life, or longer life with possibly a little less hook?
This Hoosier slick is big...
This Hoosier slick is big enough to hook up even the most powerful bracket car. Such slicks come in various compounds, for Pro Tree or three-bulb racing. Note check holes running throughout the face of the slick.
If medium compound is all your setup needs, then save your money and buy medium compound tires. Crutchfield also pointed out that one manufacturer's medium-soft is not exactly the same as another manufacturer's medium-soft compound. The only way to find out what is best for your combination is to try them out. We learned the hard way that soft compound tires don't work on our 3,400-pound 1967 Camaro. Several years ago, we bought some Hoosier 28 x 10 x 15 slicks, and had problems with the tread ripping apart. After talking to Hoosier rep Feron Lubbers, I found out why. The compound was their C07 compound, which was simply too soft for our heavy 14-second combination. The tire now comes with D05 compound, their medium-soft compound.
Stiff sidewalls are another item to consider. And sometimes, those "race track" deals from a fellow acquaintance aren't so good after all. Our friend, Brian O'Hern, who races an alcohol Footbrake car, found a great deal on a set of 14 x 32 Mickeys that had a grand total of two passes on them. What he didn't know at the time was that they were stiff sidewall tires. Stiff sidewall tires are made for cars where a quick reaction time is necessary, such as in the Pro Tree "Super" classes: Super Gas, Super Comp, Super Street, Quick Rod, Super Rod, and Hot Rod. The tire works for them because it doesn't wad up as much. They also work better on heavy, high-horsepower cars.
BF Goodrich makes this D.O.T.-legal...
BF Goodrich makes this D.O.T.-legal street slick that is perfect for Footbrakes or "street-legal"-type racers
The downside for O'Hern was the tires didn't hook as consistently with his 12-second car as well as his old wrinkle walls. However, another racing friend, Laura Brunson, tried a pair of soft sidewall 14 x 32s on her 10-second, 3,200-pound Trans Am. It didn't take long before they realized that what worked fine on a 2,800-pound machine was not so good on theirs. The car wagged its tail on the top end of the track, and when they put enough air in (13 pounds) to make it stable, the outer edges never touched the ground. They are much happier now with a set of stiff sidewall Mickeys.
Crutchfield also said that you might not want to over-tire a car if you are looking to make it go as fast as possible. For example, a 350hp Stocker shouldn't need a tire more than 10 inches wide. Anything more actually slows or even bogs the car down, due to increased rolling resistance. But he did give us another quick rule of thumb, also echoed by Lubbers of Hoosier: If you want to decrease your rpm through the traps by 100 rpm, just get a tire with one more inch of circumference-the distance around the outside of the tread. If your tire is already 91 inches around, typical of a 29-inch-tall tire, a 94-inch circumference tire, like a 30 incher, will lower rpms through the traps by about 300 rpm.
Mickey Thompson also makes...
Mickey Thompson also makes front tires for drag cars called ET Front. This low-rolling resistant tire, found on our "Lady in Red" Project Nova, is perfect for "super" racing. It is 24 inches tall.
Lubbers also noted that for bracket racing, you want the biggest tire possible. The term "wider is better" applies here. Drag Racing School professor Frank Hawley said it well here a couple of years ago: "Stuff the biggest, stupidest tire you can fit under the fender wells." What you give up in speed can be gained back in consistency.
So what about those used slicks you see for sale behind someone's trailer? Sometimes they are a bargain. For example, the owner might have bought the wrong tires. However, before you plunk down that hard-earned cash, ask yourself, "Do those tires really only have 15 passes on them? Is the compound still any good?" All reps said the heat from hard burnouts decreases the life of the compound. The tires can have check holes left, but the compound won't be as good as it should be.
Ask, "Were they stored properly?" Crutchfield said the shelf life of a slick is a couple of years if stored properly, away from excess heat or temperature changes of more than 20 to 30 degrees and away from any electric motors. Know what you are getting when you buy a used set of Comp or Super Stock tires. Do you really want a high-growth tire that's going to wear out quickly and is not as stable going down the track?
Goodyear marks its slicks...
Goodyear marks its slicks with a code found on the sidewall. That code tells which compound the slick is made of. This Goodyear Racing slick is found on a big-block dragster.
Super Stock tires are lightweight, low tread and high growth, designed for Super Stock racing, and work well in their arena. Many such tires are engineered for specific applications, but may not be the hot ticket for your combination. Be careful here. Also, unless you have a really low-horsepower car, round-track tires don't work well on straightline cars. We had a pair given to us, and they wouldn't hook up our then-14-second Camaro for anything. Although the compound was not really hard (it sure wasn't as soft as a drag slick), the sidewalls are stiffened up for cornering, which hurts straightline performance.
Several classes of racing...
Several classes of racing mandate DOT type slicks, such as this Mickey Thompson tire that has grooves in it. Such tires offer just as much traction as "real" slicks.
Front tires are a bit easier to figure out. One can find "front runners" from as short as 23 inches up to 29 inches tall. One of the first questions to ask is, "Do they fit under the wheelwells, and can I turn them all the way from hard left to hard right without hitting components?"
Footbrake racers tend to go with the taller tires, which increase rollout-the distance traveled before exiting the staging beams-and slows down the car reaction time, which in some cases prevents red-lighting. They can also use different height front tires to help "tune" their car's reaction time. The basic rule is, a shorter tire equals quicker react, a taller tire equals slower react. Unfortunately, the only way to find out is to experiment.
Pro Tree racers prefer the shorter tires, which have less rollout and give quicker reaction times. Electronics-equipped cars racing off of a full Tree usually use the shorter tire, but with a delay box, front tire selection just isn't that critical. Lubbers noted that some Pro Stock racers are now going with a slightly taller tire, a 26-incher. Although this does slow the reaction a little, it also decreases their elapsed time just a bit, which is worth a lot in that class.
Still, it is not easy to get exactly the right tire for your combination on the first try, but the reps we talked to say they can help get you into the ballpark. Also, all the manufacturers have knowledgeable people who can steer you in the right direction. If they sell you the right tire the first time, chances are you'll be back for more when it's replacement time.
But often it's up to you to determine exactly which tire is best. All said that you may have to experiment some to get the optimum tire for your combination. If you decide to call one of the tire manufacturers for help, make it easier for you and them by having your car information available. Knowing the car's weight, wheel sizes, current tire size, gear ratio, class you will be running in, and body style before you pick up the phone greatly increases your chances of getting a tire you will be happy with the first time around.
Even when you get the right tire for your combination, you still have to have a good chassis setup and follow proper burnout procedures, but that's another story.
How can you determine your actual tire size and compound? For racing tire sizes, try this formula: nominal diameter times tread width times bead diameter. Example: A 32.0 x 14.0 x 15 is a 32-inch tall, 10-inch-wide slick that goes on a 15-inch diameter wheel. Measurements are from an inflated tire under unloaded conditions.
DOT tires are similar, except sidewall-to-sidewall measurement is given instead of the tread width. Example: An 8.5-inch tread width Mickey Thompson ET Street tire is designated as 26 x 10.5 - 15. Go figure. It has something to do with DOT regulations. Most resellers list the tread width right along with the tire size to avoid confusion.
Some fronts are listed just like the rears, like 23.0 x 5.0 - 15. However, if you see a 7.10 x 15, don't panic. It's just a 28-inch-tall tire, a 29inch-tall tire is called 7.60 x 15, and a 25-inch tall tire is called 5.50 x 15.
So what do all those letters and numbers on slicks mean? For Mickeys, an "S" after the part number means it's a stiff sidewall. ST means stick shift compound. The Summit catalog notes the Hoosier stiff sidewall tire with an asterisk (*). In Goodyear's catalog or on their Web page, 1 means stiff sidewall, 2 means high growth, and 3 means Super Stock automatic. Firestone does not offer a stiff sidewall tire per se anymore, but they do have a special compound, F14, for stick shift cars in the Stock classes. Mike Crutchfield noted that where allowed, manual gearbox racers are building in slippage to the clutches, so that many combinations don't "know" whether they are being hit with a transbrake or a clutch.
A "W" after the size designation for Hoosier, Firestone, and Mickey Thompson means the tread is wider than the nominal number given in the tire size. In addition, the Summit catalog noted that an "A" after the part number indicates 2 inches added width.