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Don’t Blow It—We Turn To the Pros for Proper Bead-lock and Slick Tube Installation Tips

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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.

One of several Mickey Thompson employees that are on hand at events all over the country, Buddy Legath knows all of your dirty little wheel and tire secrets as soon as you drop off your gear at the M/T trailer for service. We’re here to make sure you don’t get in trouble.
While the M/T guys are on hand at most major events, they can’t be everywhere and some racers opt to mount and balance their own tires. Here are the essential tools you will need to get the job done. The 16-inch-long tire spoons can be found at most motorcycle tire supply shops.

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.

If you notice your drag radials slipping on the rim, but aren’t sure that you want to step up to a set of bead locks, racers are known to use Permatex high-tack gasket sealant around the bead of wheels where drag radials will be used without a bead-lock. Ideally, you apply the high tack, air up the newly mounted tires, and allow them to sit overnight before using them.
Moving on to the proper way to install bead locks, we begin the process with Legath using a chalk or crayon to mark the tire rotation on the sidewall, and he then mounts the tire on the wheel while making sure the rotation marking is located at the valve stem—it’s easier to notice it there as you are likely to check the tire pressure quite often.
To get the tire on the rim, start by dropping the tire over the large part of the barrel so it hooks on the inside of the barrel. This will give you some leverage to pull it over the other side.
Should you feel like you are struggling to get the tire on the rim, Legath suggests trying a different approach rather than forcing it to work. With this wheel, he had to flip it over and was able to get it on from the opposite side.
Once the tire is on the rim, make sure the bead is sitting flat and even in the bead channel of the rim. If the bead is not flat, the balance will be way off, as will the clamp crush and air sealing capability. Different tire companies have different thickness of beads, and the bead area of the wheel can vary from manufacturer to manufacturer. M/T likes to see a clamp crush from the bead lock of .080-.100 inch, but you should check with your particular wheel manufacturer for their recommendations as well. You can check the amount of crush by measuring the tire’s bead and the bead lock gap without a tire. Without the proper amount of crush, the bead-lock will not be able to do its job.
Before you put the bead lock on the rim, be sure to give the fasteners a coating of anti-seize.
It’s ok to use an impact gun on the fasteners provided you are only running them down to snug them up. They need to be properly tightened with a torque wrench to 22 lb/ft (or per the wheel manufacturer’s recommended amount), and an impact will likely blow right past that if you’re not careful.
Bead lock fasteners should be snugged down in a star pattern, followed by final tightening of every other bolt until all are tightened completely.
It should go without saying that before you dismount the tires on your bead-lock wheels to make sure you deflate them before doing so.
Many racers keep a bubble balancer in their trailers, as does the M/T staff. To use it, the deepest side of the wheel should face down. Buddy doesn’t recommend spin balancing for bias-ply tires or radials. Stick-on weights are preferred, and Legath recommends using Gorilla brand duct tape to secure the weights to the wheel as an added measure.
A regular at big heads-up races all over the country, Mac Fab’s Thomas Kirk (at Left) and his right-hand man, Aaron Brown, can install bead locks on your standard bead drag racing wheels and company comes highly recommended by the M/T staff. Installing bead locks is a precision job (remember that .080-.100-inch of crush we talked about earlier), so don’t think that just because you’re handy with the TIG welder that you can whip out your own locks—there is certainly a significant monetary loss if you have to scrap them and buy new ones.
Mickey Thompson offers tubes for bias-ply slicks for sale, and they are generally used for higher horsepower and heavier vehicles as the inclusion of them helps stiffen the sidewall and maintain its shape when the throttle is down. This helps prevent deformation and the tire shake that is often a result of that. The white line that is noticeable in this image on the side of the tube should face the bottom or inside half of the wheel.
The tube installs only one way as the valve stem is offset.
A mild application of baby powder allows the tube to expand freely during inflation and prevents the tube and tire from sticking to each other under heat.
Lay the tube in and make sure it is not pinched anywhere. Then mount the tire to the rim and check the tube again to make sure it has not shifted.
The valve stem hole in the wheel must be 5/8-inch diameter. This is to allow the rubber on the valve stem base to poke through, which in turn allows the grooves in said base to dissipate any air between the tire and the tube. Air in between will cause a secondary reaction and make the tire bounce back rather than wrinkle like it should at the hit.
With bias-ply slicks, you’ll need to measure the rollout to make sure the tire circumference is the same from side to side. Put 20 psi of air into the tire to obtain the initial stretch and then fill the tire to the normal operating pressure, around 12.5 psi. Using a tape measure, determine the circumference of the tire. A half-inch of difference between the two rear tires is acceptable, though M/T’s Legath usually shoots for 1/8-inch. If the rollout is more than the half-inch, the car will drive to the side with the shorter or smaller diameter tire. If a tire needs to be stretched more, you can go up to 30 psi (maximum). Going beyond that will not stretch the tire. An added tip from M/T, cars making 1,000-1,500 hp should rotate the tires every pass. Cars with a horsepower level below that should rotate every 20 passes or so.

Sources

Mac Fab Performance Bead Locks
919-774-1297
www.beadlockconversions.com

Mickey Thompson Tires
www.mickeythompsontires.com


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