Maximizing Wheel Sizing on an S197 With Forgeline

Wheels can make or break the appearance of a car. More than that though, wheels can also dramatically affect how a car performs, whether that is on the street, or at the race track. The right wheel package allows for the maximum amount of tire you can fit under the fenders safely. Combined, these two can result in exactly the desired performance an enthusiast is looking for.

Our 2013 Mustang GT, Project Silver Bullet, is one that must do more than just look like another ROUSH RS3 clone. We’re pushing the limits of what a daily drivable Mustang can do with this car. With just over 500 hp already on tap at the wheels, and a Maximum Motorsports suspension to help us hug the corners harder, it’s now time to couple that with the next piece of the puzzle. For that we turn to Forgeline, and Mickey Thompson, to make sure we order the right wheels the first time.

Our rendering by Jim Gerdom of Design Factory Art shows the final product with our Forgeline wheels installed. Jim Gerdom also specializes in one of a kind, limited production art prints along with renderings like ours.


We’re installing Forgeline SC3C wheels on our Project Silver Bullet

SC3C Wheel

We are outfitting Silver Bullet with a set of Forgeline SC3C wheels, finished in Gunmetal and Transparent spoke. These wheels offer a modern high performance look, but blend well with the lines of our 2013 Mustang GT and it’s retro-modern styling. They should also nicely compliment the ROUSH body kit what we’ll be installing down the road.

Forgeline offers these wheels with a staggering number of options making them truly customizable for the look of the car and the owner’s tastes. Options include exposed or hidden hardware. The wheels can be ordered with or without a stepped lip. Virtually any part of the wheel can be coated, machined, or polished as well. There are almost endless options to choose from as each component of the wheel can be finished differently, meaning a wheel can have one type of finish on the lip, a different finish on the spokes/center, and a third option for the inner rim shell. If you really wanted to go hardcore and unique, a Center-Lock conversion could add that missing touch. Of course this is really done with racers in mind, allowing tire changes to be sped up. Still it offers a clean look to the wheel with no visible wheel mounting holes.

Our wheels measure a monstrous 20 x 10-inches front and 20 x 11-inches rear. The wheel design is concave with a stepped lip for a deep look. The mounting pad is located inboard of the the outer rim to give the wheel a deeper appearance. The five split spoke design, with beveled edges, and hidden hardware will lend well to the modern appearance we have in mind for the car. These wheels start at $1,530 for the 20 x 10, and add $150 for the Transparent Smoke finish, plus another $75 for the gunmetal outer powdercoat.  Our 20 x 11 wheels price starts at $1,550 before those same options.

The SC3C wheels feature hidden ARP stainless hardware. Right: The mounting pad is located inboard of the outer rim to give a deeper appearance.

Forgeline builds all their wheels at the company’s Dayton, Ohio facility, from T6061 aluminum. This gives the wheel superior strength and lightweight. As with all Forgeline wheels the center for the SC3C is cut on a CNC mill, after it has been machined to size on a CNC lathe. The final product is hand assembled with ARP stainless steel fasteners, and sealed to prevent leaks.

Selecting The Proper Size

Running the same size wheel and tire package allows for longer tire life because the tires can be rotated, while still giving the car a good balance for handling. -Steve Schardt, Forgeline Wheels

Selecting the proper wheel package is all about balancing the grip needs of the car with the car’s power. For example in lower power or near stock applications keeping the wheel sizes closer to each other allows for better acceleration and handling. When the rear tires are larger than the front, in a lower powered car there is more grip from the rear tires, that translates to front end push in the turns. Mustangs already have a push issue in high speed cornering from the factory. That pushing translates to poor handling because of understeer and increases tire wear. Staggering the wheel and tire package in a lower powered car will make that issue work.

In higher powered street cars though the opposite is true. In high horsepower cars a wider tire is needed in the back because of the higher output of the car. This is necessary to provide enough rear grip and balance the handling properly. By balancing back out the tire sizes with the horsepower of the car, the car can apply power more effectively when exiting a corner.

Left: Our SC3C wheels measure 20x10-inches front and 20x11-inches rear. Right: Our backspacing is 38mm front and 55mm rear. The wheel mounting pad is built into wheel center when it is cut on the CNC mill.

Steve Schardt from Forgeline reinforced these recommendations. As a large supplier of wheels to the racing world, Forgeline sees a variety of vehicles using their wheels. Schardt mentioned that Mustangs that they supply wheels to competing in the Grand-Am Continental Sports Car Challenge are all running the same wheel size. Doing this not only keeps the car balanced but as Schardt tells us, “Running the same size wheel and tire package allows for longer tire life because the tires can be rotated, while still giving the car a good balance for handling.”

Selecting A Wheel

Under Pressure

Our 2013 GT came factory equipped with a tire pressure monitoring system (TPMS). This particular factory system uses pressure monitors that attach to the factory rubber valve stems. Our Forgeline wheels use metal valve stems that will not attach to the factory pressure sensor. Forgeline resolves the TPMS issue by building the wheel with a mounting location for the factory TPMS sensor. This allows retention of the factory TPMS system, and won’t trip a warning light on the dash. This bracket for the sensor is a no-cost option on certain Forgeline wheels, including our SC3C.

Schardt says that when customers contact Forgeline the first question asked is what is the purpose of the car, “The first determining factor in wheel selection is does this car need a wheel for the track, for street and track, or just a lifestyle wheel.”

There are a few other factors. As we mentioned the vehicle’s horsepower is a key factor in determining the wheel sizes. Schardt also mentioned tires, “Some customers want to use a specific tire or tire size, in those cases we look at the recommended rim size for that specific tire.” After discussing wheel sizing with Schardt, we ordered our Forgeline SC3C wheels. With our slightly staggered fit, they should give the car good handling balance, and optimum grip when cornering with our growing power goals.

Mickey Thompson Street Comp Tires

We have discussed Mickey Thompson’s Street Comp tires at length in two previous articles. The result of an extensive research and development program, the MT Street Comp tires offer excellent handling under a variety of weather conditions, and excellent wear for an Ultra High Performance Tire.

With a Uniform Tire Quality Grading of 300 AA, these tires not only offer outstanding treadwear, and excellent dry condition handling, but also excellent performance and stopping ability during wet weather as well.

The first determining factor in wheel selection is does this car need a wheel for the track, for street and track, or just a lifestyle wheel. -Steve Schardt, Forgeline Wheels

According to Schardt, in the past finding a quality UHP tire that could handle was often a limiting factor in selecting a wheel package. However with the MT Street Comp we’re covered, we chose 275/35/20 tires to go with our new Forgeline wheels.

These tires should provide us with the best combination of quiet ride for our daily commute that won’t beat the fillings out of our teeth. We’ve yet to wear out the set on Project Wild E Coyote, though it’s not for lack of trying. This gives us hope that Silver Bullet should be able to use these tires for quite some time to come.

The Mickey Thompson Street Comp tire is set to become the darling of the aftermarket performance world. We have used these on two previous project cars with great success. For Silver Bullet size 275/35/20 was chosen for all four corners.

We know from our previous testing that these tires provide excellent cornering grip, and we expect great things from them when we hit the autocross and really push them to their limits. Working in conjunction with our Maximum Motorsports suspension system, this should make an ideal handling package in our quest to have one of the fastest, and best handling Mustangs on the streets.

Mounting and Balancing

We mounted and balanced our tires in house. Forgeline does offer wheel and tire packages for customers who want their tires mounted before they’re delivered as well. Since our 2013 Mustang came with a factory tire pressure monitoring system, Forgeline built our SC3C wheels with an internal mount for the monitors. On our stock wheels the sensor is mounted to the valve stem, however for our SC3C wheels, we simply leave the pressure sensor and an original valve stem together and mount them to Forgeline’s internal TPMS mount. We then used the Forgeline-supplied valve stems with our new wheels.

Top: Power Automedia shop head honcho Sean Goude mounts and then balances our Forgeline wheels and Street Comp tires Bottom Left: The factory TPMS sensor and valve stem mount on the inside of the wheel shell. Bottom Right: Dean installed the wheels and torqued them by hand to prevent damage to the wheel, the brakes, or the hub.

We balanced our wheels with stick on weights, and installed them on the car. Each wheel was torqued by hand in a criss-cross sequence to ensure that it wasn’t damaged during installation, and didn’t distort our brake rotors by putting an uneven load on them.

Test Drive

On the street we immediately noticed a difference with how the car feels. Our Maximum Motorsports suspension has already given this car much better handling. Now with the wheels and tires to match the suspension’s performance we feel more confident than ever in the way Silver Bullet handles. Once again the MT Street Comp tires deliver good, quiet ride and confident handling. Our Forgeline wheels look incredible and really set the car apart from the crowd. They also give us confidence in knowing that whether we’re on the street or the track they won’t fail. Having the wheels and tires matched as a carefully selected package means Project Silver Bullet is one step closer to completing it’s mission.

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About the author

Don Creason

Don Creason is an automotive journalist with passions that lie from everything classic, all the way to modern muscle. Experienced tech writer, and all around car aficionado, Don's love for both cars and writing makes him the perfect addition to the Power Automedia team of experts.
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