Weld Racing’s RT-S Series Wheels: 10,000 Fitments Can’t Be Wrong

How many times have you been to a car show and seen a beautifully built muscle car with a killer motor, maybe a couple of turbos, flawless paint and absolutely gorgeous in every aspect…until you get to the wheels and realize this brutish car has some really weak knees for wheels? Too many times we’ve seen a car that is put together extremely well, with monstrous horsepower, and a wheel that shouldn’t be allowed to try and support that kind of stress. Perhaps you suspect that you have a set of weak kneed wheels or if terms like “flywheel” effect, dynamic and radial balance are unfamiliar to you, or maybe you would simply like to know how the placement of weight in a wheel can lower your ET, then read on.

Everyone gets to the point where they want to customize their project car or even stock vehicle and make it different from everything else on the road. Maybe you want to change the look of your car or improve the performance with wider tires. For some types of cars, especially the vintage muscle cars, the options have been limited. Economical selections were based either on custom looks or improved performance depending on what fit in the wheel well or fit with your brake calipers. The alternative was ordering a very expensive set of custom wheels made to order.


A cross section of the three different mounting pads show the room available for brake caliper clearance. With a wide array of offsets and widths available, Weld's RT-S series has a mind numbing amount of possible size combinations.

No more compromising

For off the shelf shoppers, the days of choosing between aesthetics or performance, or worse yet, compromising in wheel selection are over. We checked in with our friends at Weld Racing to find out what was new in the world of performance wheels and we discovered a new line of wheels that has all the engineering tricks and secrets that Weld uses in Late Model circle track wheels, Sprint Car wheels, Drag wheels and street performance wheels incorporated into a newer forged, three-piece modular welded wheel that costs less than their highly successful RT line of wheels.

Along the way we got an education in what makes a great wheel. Don’t misread what we’re saying here. Weld Racing is not trying to re-invent the wheel, they just have taken advantage of modern technology and forty plus years of racing experience to perfect wheel design.

Weld Wheels has designed a new style of wheel based on their very popular RT series that opens up the door to over 10,000 different fitments with the RT-S series. “Virtually any vehicle from 1930‘s hot rods to 2011 muscle cars are covered,” says Weld Racing’s Director of Marketing, Gregory Smith.

We talked to Weld Racing’s VP of Sales and Marketing, Kyle Fickler, about the latest release from the company, ”The RT-S is a street-strip wheel… actually, it’s more than that. We’re still trying to figure out what it won’t do. We’ve had it on drift cars, drag race cars, street rods, BMWs and you name it. We’ve found a way to fit all different applications,” said Fickler adding, “like all Weld Racing Wheels, it’s made in the USA.”

After seeing an early release of these wheels at the 2010 PRI Tradeshow in Orlando, we wanted to get a closer look at the details on these wheels and pick up a set for our very own classic muscle car, a ’69 Camaro project car with a surly attitude and very bad intentions.

Watch Weld Racing’s SEMA Tradeshow Video Where The RT-S Series Wheel Was Unveiled:

Why Weld Racing Developed The RT-S Series

With an already existing, and very successful RT Wheel line of wheels on the market, we wanted to know why Weld Racing developed a new line of wheels based on the same type of technology. Smith explained the idea behind the RT-S line, “We developed the RT series three piece modular wheels as the next generation of street and race wheels with increased strength for the rigors of street use. Our customers began asking for a wheel that could do all the things that the RT wheels could do, cost less and available in larger diameters. We listened and a year later, the RT-S series was born.”

Weld Racing showed the different designs available in the RT-S series of wheels at the PRI tradeshow in Orlando last year.

Smith also explained the technology behind the RT-S wheels. “In addition to years of racing experience in wheel manufacturing, we use Finite Element Analysis (FEA) to understand that a wheel can be too strong in some areas and removing mass in that area spreads the load more evenly across the surface, which makes the wheel stronger as a whole. The goal is to make the wheel as strong as necessary for the intended application but at the lightest possible weight with a factor of safety in place. Many people don’t realize it, but Weld Racing places a high emphasis on driver safety. We want everybody to go home at the end of a race.”

Safety almost always carries a bigger price tag with it and professional racers have accepted that when it comes to quality products, you generally get what you pay for. Street enthusiasts tend to compromise more between cost and safety, and for the most part, it is not an issue. However, an enthusiast that wants higher performance on the street or a weekend warrior that takes his street machine to the track doesn’t want to compromise too much between cost and quality. This is where the genesis for the RT-S series came from.

Casting Doubts

The difference between casting and forging is well known and documented, so there is no need to go into the quality of forged wheels here other than to say that Weld Racing utilizes the forging process to create a stronger wheel with less weight for a very durable rotating component.

According to Smith, “The RT-S Wheels are three-piece forgings, which is done for application flexibility, that are assembled by welding. The flexibility in application means that there is a large array of widths and offsets along with three mounting pad heights for a mind numbing amount of possible size combinations. The three choices of mounting pad heights are for brake caliper clearance so you can use anything from drum brakes to billet 6 piston calipers.”

How Weld Racing goes about manufacturing the RT-S series, as well as the other Weld series of wheels, is by using quality materials. “Primary forging grade aluminum alloys are used to create these racing wheels and this means that no recycled scrap is used. The difference in quality is obvious from the appearance, the strength and the durability,” said Smith.

Ken Kurtz won the next two races after switching to Weld Racing's RT-S series wheels.

Evidence of the RT-S Wheel’s reliability in racing was apparent in May when USTCC-GT racer Ken Kurtz returned to NASA racing after experiencing wheel failures earlier in the season. Changing to the Weld Racing RT-S wheels, Kurtz raced his way to class victories in two consecutive days at Thunder Hill Raceway in California, in his first outing on the RT-S wheels. lsxmag.com covered Kurtz’s return to racing on the new wheels. The article can be viewed by clicking here.

Speed Sells

Weld Racing engineers use FEA three dimensional modeling when designing wheels. FEA programs can help find thermal "hot & cold spots" to predict where more material can be added or taken away from the design.

While the company does focus on driver safety, Smith also acknowledges that “Speed sells. Our products are designed with safety as a concern but we also design them to enhance the performance of the car.”

Weld’s engineers design a wheel in a computer aided design program using experiences gained in decades of manufacturing wheels for racing. Once the wheel is designed in the computer program, the design is loaded and constrained in an Finite Element Analysis (FEA) program. “The answer to making a wheel lighter and stronger is not always obvious. Our engineers use a lot of three dimensional contours, along with forty years of racing data to serve an important role of understanding how to spread the load while minimizing the ‘hot spots’.”

It doesn’t begin and end with the FEA three dimensional modeling and designing however, “There’s not 100% correlation between FEA and the real world,” Smith says. “We have an in-house test center, and we use it to test the limits on a regular basis, right here on our test machines. When we think we have a perfect design, we will put the wheel on a radial test machine, a stress test machine and we do an impact test. All those things happen and we learn from those results. We factor in what we learn from physical testing back into the FEA process.

The end result is that we get a lot faster and more efficient when we bring a new design to the marketplace. That efficiency means that we can bring an well designed and affordable wheel to the public.”

Working With Other Companies As One Team

Smith clued us in on what makes Weld Racing’s engineering cutting edge; “We do a lot of information sharing with other companies that have a direct relationship with our products. Our team works with brake companies and tire companies to understand how our wheels work with their components and visa-versa.”

Companies working together and doing R & D with each other is nothing new, especially when it produces a complete package that dominates a sector of the sport. “We typically see companies that are on the cutting edge working with each other,” says Smith. “The reason why is because they are always coming up with something new, breaking new ground, and not just copying another product,” he added.

The RT-S series handles street or strip applications equally well. Here the S-71 model RT-S wheel is used on the Erickson's 2001 Chevy S-10.

Weight a Minute!

Weight is a big factor on every high performance car, especially those bound for the track. Engineering racing wheels is often a compromise between weight and strength with lighter wheels having a positive impact on many facets of overall performance. From acceleration, deceleration, braking and cornering, a lightweight and strong wheel will show performance gains.

Weld Racing's RT-S series is available in the S-71 "Weldstar" design in polished or black anodized center and the S-74, a sophisticated Y-spoke design, with a black anodized center.

According to Smith,”To understand the full impact of less weight, Weld engineers look beyond static weight, or weight that can be measured by a scale. Taking the principals of physics into consideration, we use quantifiable physics concepts like Rotational Moment of Inertia (RMOI). Most racers know this concept as the ‘flywheel effect’. On some occasions, we may be a little heavier on the scale to meet all of our objectives, but rest assured our goal is to win the RMOI race with each wheel we design and manufacture.”

To illustrate how the “flywheel affect” plays a role in wheel weight, Smith used a common analogy of a figure skater spinning in a circle. “An ice skater spinning on a verticle axis with arms extended will spin one speed and as the skater pulls their arms closer to the axis center, the speed of the spin will increase. That’s because of angular momentum, which in very basic terms is the distance of the mass from the center. It works the same way in wheels.”

Taking advantage of the “flywheel” effect, Weld Racing focusses on where to place the mass on the wheel. In order to totally control the mass, Weld manufactures every piece of the wheel onsite. “We make our own rim shells. That’s another area where we are unique. Many wheel companies buy rim shells from another company. We build our own rim shell in-house to do exactly what we want it to do. We take a forged piece of billet that has the grains running out like the spokes on a wheel, and cut a center section, then we build our own shell to put around it. It is fully designed, engineered and built to exactly what we want, right here under one roof,” Smith stated.


The RT-S series works well on any muscle car from any period. "We're still trying to figure out what it won't do," said Weld Racing's VP Kyle Fickler.

You Gotta Have Friends

Building a good quality wheel is one thing. Building a good quality wheel that works exceptionally well with all the other components, like tires and brake calipers, is something else. We asked Smith how Weld Racing was able to have RT-S wheel fitments for practically every type of vehicle.

Smith responded by saying, “We are good partners with companies like Wilwood and Baer Brakes. We have long relationships with them. We also have very long relationships with tire manufacturers. What they do affects us and what we do affects them so there is a lot of research and development that occurs between the companies. A good example of this cooperation between companies is our bead lock ring for Mickey Thompson tires. Mickey Thompson tires have a smaller bead knot and require more clamping force than other tires. They have a different tire than their competitors and a lot of people run them, so we had to make sure that people using Weld Racing wheels could use Mickey Thompson tires with the proper clamping.”

Smith explained how tire, brake and wheel companies working together ends up with a multi-purpose product like the RT-S wheels, “Many times a company will send us a prototype part to see if it fits on our wheels and what changes they need to make to ensure a proper fit for the end user. Conversely, we make prototypes for brake and wheel companies to ensure that all of our components work well together. Because a customer is likely to be using all of our products, it’s in all of our best interests to work together to give the end user the best possible combination of products,” he said.

All of this cross research and development has ended up with the RT-S wheel line covering three different brake pad heights, several different wheel offsets, different widths and different finishes for more than a total of over 22,000 different and unique combinations to accommodate anything on the road.

Highlights of Weld Racing’s RT-S Wheels:

  • Three piece welded modular design
  • Available in three pad heights for brake clearance with many sizes of performance brakes
  • Widths from 3.5 inches to 18.0 inches
  • Diameters include 15, 17, 18, and 20 inches
  • Wheel centers are CNC-milled forged billet for extra strength on high horsepower vehicles

Weld's RT-S wheel in the classic Weldstar design installed on a Z06.

Getting It Right With Coordinated Effort

When it came to getting our classic muscle car outfitted with wheels, the obvious choice was the Weld Racing RT-S wheels. The large number of different fitments combined with an affordable very strong wheel that could be used in street performance, road racing, drag racing and still be classy enough to stop a crowd at any car show made the RT-S wheel an easy choice. The added bonus of knowing that Weld Racing partners in information sharing with the other companies that we planned on using for suspension and braking gave us a pretty decent comfort level that all the parts would work together without modifications or trial and error. Getting it done right the first time makes a project build so much more pleasant.

About the author

Bobby Kimbrough

Bobby grew up in the heart of Illinois, becoming an avid dirt track race fan which has developed into a life long passion. Taking a break from the Midwest dirt tracks to fight evil doers in the world, he completed a full 21 year career in the Marine Corps.
Read My Articles

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