How to Select a Tire - Tire Talkin'

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.

Rear Tires

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.

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.

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.

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.

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.

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?

Front Tires

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.

Other valuable sources of information are available on the Internet. Check out www.goodyear.com and look under "race tires" for information on their entire line of racing tires. Hoosier offers a similar deal at www.hwwe.com, under the tire specs button. BFGoodrich Drag Radial information can be found at www.eurotire.com/goodrich. M&H Racemaster has a single Web page at www.goracing.com/racermall/m&h.

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.

Determining What's What

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.