Safety third, as the saying goes. What is likely the most critical aspect of any racing operation is often pushed down the priority list, but sometimes safety goes hand in hand with maintaining and even improving performance. During a conversation with our friends at Mickey Thompson Tires, they expressed concern over the frequency with which they see improperly mounted tires on drag wheels, and it was obvious that we needed to work with them to show our readers the right way to do things.
Bead-lock wheels are often necessary both on drag strips as well as in off-road applications. They grip the tires and hold them in place when an extreme amount of torque is applied and traction is at maximum. Without bead locks in these situations, the tires can rotate on the wheels, which causes a loss of traction and can even deflate the tire in some circumstances. There is a bit more to buying bead-lock-equipped wheels than you might think, and talking with both the wheel and tire manufacturers is essential to getting a combination that works as expected.
If buying another set of wheels isn’t an option, you can have bead locks welded to you current wheels. Companies like Mac Fab offer this service, and Mac Fab can often be found at many of the big heads up races throughout the year—they can even install the bead locks while you’re at the track. Whether you buy a new set of rims with bead locks or have your current ones modified to accept them, attention should be given to the installation procedure, which we’ll document in the photos to come.
Another drag racing combination that Mickey Thompson was concerned with is the bias-ply slick and inner tube. There is more to the installation than just stuffing the tube in the tire and inflating it. Doing it the wrong way can result in the car bouncing at the hit, and cause a vibration down track, which is something M/T regularly sees as the biggest issue with improper installation. Premature failure of the tube itself is also a possibility. Fear not, though, as we’ll walk you through M/T’s recommended procedures to ensure you have a proper performing wheel and tire combination.
Screw the Radials—Just Don’t Do It
At some point in time, racers using drag radials took a page out of the bias-ply slick racer handbook and thought they should screw the drag radials to the rim to prevent them from moving on the rim—this in lieu of having a bead-lock wheel that accomplishes the same thing, but safely.
The issue with putting screws into a radial is this—the softer, more flexible sidewall of the bias-ply tire absorbs the shock of the tread or contact patch gripping the pavement better than the radial does. The stiffer sidewall of the radial tire is more efficient at transferring the energy from the axle to the pavement—this is what makes it generally the faster tire of the two—but that stiffness and efficient transfer of power results in a much greater force being exerted on the bead, and thus the bead of the tire is forced along the edge of the rim despite the screws trying to hold it in place.
Having screwed the drag radials, racers are not likely to bother checking for tire slippage, and it wouldn’t exactly rear its ugly head until you dismounted the tires to replace them. That said, there have been extreme cases where the tires spun on the wheel, the screws shredded the bead, and the car went out of control due to a sudden loss in tire pressure.
The included pictures above are a relatively mild example of this situation, but as you can see, the screws are not preventing the tire from spinning on the rim. Had this racer not needed to have his tires changed, things could have gotten much worse in the near future.
If you find that you are spinning your drag radials on the rim—whether you simply mark the wheel and tire or find an anomaly in data from a logger—then it might be time to step up to a bead-lock wheel.