Wheel manufacturers set tougher-than-required standards

Wheels used in NASCAR rarely get mentioned in race coverage. And that's a good thing for the manufacturers that exceed minimum safety standards.

Updated: September 26, 2008, 3:23 PM ET
By Bill Borden | Special to ESPN.com

One area on a Sprint Cup race car that you seldom hear mentioned as being a problem is the wheel or rim that is used to hold the Goodyear tires. Most parts manufacturers probably don't want their product's name mentioned during a race because it usually means there has been a problem with it.

In my 28-plus years in racing I can only recall a couple of times when a wheel failed because of a manufacturing defect. And those instances were many years ago.

NASCAR's strict rule specifications and improvements in materials, design and construction have made the Sprint Cup wheel almost bulletproof. Even when a pit crew occasionally fails to get all of the lug nuts tight on a pit stop, the wheels hold their shape under tremendous side loads as the cars go into the corners.

The wheels can only be supplied to the teams by a NASCAR-approved manufacturer that has submitted its wheels to NASCAR or SFI -- a leading safety foundation -- for testing and approval. However, most of the approved manufacturers do their own testing as well and set standards that are higher than those required by NASCAR or SFI for an added margin of safety.

Aero Race Wheels, Inc. an approved wheel supplier in Estherville, Iowa, is one of the companies that test their wheels in-house at their facility, said Wayne Redmond, a big wheel with the company.

Asked if it is very difficult to build a wheel that meets all of NASCAR's specs and can survive the rigors of Sprint Cup racing, Redmond said the rim shell or the part that the tire goes on is made in seven different stages.

"The actual disc or center of the wheel is produced in a press utilizing six different pieces of tooling," Redmond said.

After that the disc goes to the machining department and goes through two processes involving a computer numerical control lathe and a CNC machining center. [Sounds simple enough.]

After all of the forming and machining is done, the rim shell and disc -- the two components that make up the wheel -- are thoroughly cleaned and inspected at several quality control stations before they are approved for assembly into a wheel.

The actual welding of the disc to the rim shell is done in 10 different operations at Aero to ensure that it is done properly and the wheel is true. [It's getting a little more complicated isn't it?]

Redmond said the wheel is ready for the coating process once it has been assembled, cleaned and inspected by quality control. The coating process takes three stages to complete. Then it is back to quality control once again where the wheel is put on a machine that checks the radial and lateral run out or how true the wheel is in thousandths of an inch. [OK, so it is a little more complicated than I thought.]

But wait; three stages are still to go. The final three stages are to install the valve stems, pinstripe the wheel and install the decals. Now the wheel is finally ready for shipping to the customer or to the corner fatigue machine for testing to guarantee that it and its fellow production wheels meet necessary standards.

The corner fatigue machine simulates the wheel on the right front of the race car going through the corner because that is where the wheel experiences its greatest load factor. The SFI/NASCAR test states that the wheel must be able to withstand a 3,500-pound load for 250,000 cycles [complete wheel revolutions] to be approved for competition. Aero uses a 4,400-pound load for 500,000 revolutions test on their products to make sure they will not fail.

It's a very strict and controlled process, outlined above, to create the race wheel and get it to the team. So what happens once the wheels are in the teams hands? First of all, most of the teams have an independent contractor to handle the wheels from week-to-week. These independent contractors will transport the wheels to each race, deliver them to Goodyear for tire mounting and delivery to the team at the track.

Then, after the race, the contractor will pick up the wheels from Goodyear after the tires have been dismounted and clean and inspect them and repeat the process for the next race.

[+] EnlargeRims
Andy Lyons/Getty ImagesEach team imprints their car number on the inside rims for identification and places a bar code on each wheel to track its individual history.
NASCAR requires each team to identify their wheels with their car number imprinted on the inside rim. And the teams place a bar code on each wheel to track its individual history.

Most teams will start the season with 240 wheels per car, Redmond said. That seems like a lot of wheels to keep track of during the season for each team and their contractors but the bar coding makes their collective lives simpler. A team member is in charge of keeping track of each wheel, how many laps it runs during a particular race and what, if anything, happens to it during that race. For example, a tire may blow out and cause the wheel to make direct contact with the racing surface. That would normally be the end of that wheel's life in Sprint Cup.

If a particular wheel does not experience any unusual event such as a crash or flat tire or loose lug nuts, etc. then its normal life expectancy is between 400 and 700 miles before it is replaced in the rotation. A wheel may only be run a few miles during a particular event if there is a quick caution and the team elects to put on a fresh set of tires. Or it might go a complete run before the next set is installed.

The Goodyear tires are designed to provide good grip for a little bit longer than a normal fuel run, which means the most a wheel would normally be used would be about 60 to 70 miles per cycle. That is far short of the test requirements dictated by NASCAR, SFI and the wheel manufacturers so that is probably why you seldom hear anything about a wheel failure during a race.

Some tracks are much more stressful on suspensions, wheels and tires than others. Bristol is the best example of the extreme punishment the tires and wheels might experience during a race. Flatter tracks and road courses are also more punishing because of the added lateral G forces experienced on flat tracks or the varying left and right forces experienced on a road course.

Even during its short life, the race wheel is more likely to experience far greater stresses than your wheels on your street car because of the extreme G forces imposed on a race car as it goes through the corners at high speed.

The fact there are so few wheel failures during competition speaks volumes about NASCAR's and the manufacturers' commitment to safety. The last thing a driver wants to worry about is losing a wheel in a corner at high speed. That could hurt a lot more than losing a tire because if the tire goes flat it only drops down to the wheel rim and still gives the driver some opportunity to maintain control.

Otherwise he will be singing "You picked a fine time to leave me loose wheel!" Just visualize ole "DW" singing that little ditty off key and you can begin to see just how painful losing a wheel could be for a driver.

Bill Borden is a former championship winning crew chief who operated David Pearson's Racing School for many years.