Changing the wheels and tires on a car is one of the easiest mods to do which not only changes the look, but has the potential to affect the performance of the car and its ability to lay down that four-figure power output. When it came to selecting wheels for Project Boosted Coyote, a 2015 Mustang GT seeking 1,000 hp, Ivan wanted a 20-inch wheel and wanted to put the widest possible tire in the rear.
Selecting wheels can be tricky, and it’s crucial to understand wheel basics to get the appropriate wheel. We worked closely with Forgestar and Toyo Tires to dial in Project Boosted Coyote and wanted to share a few tips along the way.
Staggered Setup or Standard Setup?
Many people prefer the aggressive look of a staggered wheel and tire set up, but this comes with the caveat of not being able to rotate your tires to promote even wear. The rears will be replaced more regularly than the fronts.
However, staggered wheel sets also come with performance benefits like better grip off the line for lower e.t.’s and improved traction coming out of a corner (for those that prefer to turn, not just go in a straight line).
Often, serious drag cars have large tires in the rear with skinnies up front. The reason for this is simple: drag cars go in straight lines. They don’t need to turn, and thus don’t need a large amount of grip up front to counter the forces of turning. Running a skinny tire up front saves weight and is less rolling resistance, thereby shaving some more time of the run.
In some handling applications, there can be a benefit to having a “square” wheel and tire setup as it helps maintain better balance. But for Ivan, a wider rear tire could be the difference between safely pulling onto a road or planting the car in a ditch.
Staggered or square? Your driving style and willingness to replace tires should be the deciding factor.
Wheel Specs: How Wide Can I Go?
The car’s estimated 1,000 horsepower means it gets a dedicated race tire for the drag strip, but to remain a daily driver the car requires a fat and sticky rear tire. Wide tires mean there is a larger area of contact with the asphalt which helps keep the car safe and enjoyable to drive.
While wider wheels can provide better handling and stance, they can also cause potential issues with steering and suspension components, making it essential to get the correct fitment.
On a stock vehicle, the front of an S550 Mustang can’t take anything more substantial than a 9.5-inches wide wheel. Anything wider will cause a significant amount of tire rubbing on either the inside or outside.
Meanwhile, in the rear, an 11-inch wheel is the widest bolt-on wheel available for an S550. Any wider, and you’ll have to start modifying the car with flairs or mini-tubs to make them fit. To prevent any rubbing or poking, Ivan needed his wheels to have a minimum 55mm offset.
What is Wheel Offset and How is it Different from Wheel Backspace?
The “offset” is how far the centerline sits from the edge of the wheel. Backspacing is the distance from the back edge of a wheel’s rim to the mounting surface of the center hub.
Measured in inches, backspacing is closely related to offset in that changing one affects the other. The offset is the distance from the hub surface to the centerline, and backspacing is distance from the back of the wheel to the hub surface.
There are three types of offset:
Zero Offset: Mustang wheels with zero offset means the hub-mounting surface is even with the centerline of the wheel.
Positive Offset: The hub-mounting surface on your Mustang’s wheel is toward the front (face or “wheel side”) of the wheel. Positive offset wheels are generally found on front wheel drive cars as well as on newer rear-wheel drive cars.
Negative Offset: Having negative offset on your Mustang’s wheel means the hub mounting surface is toward the back (or brake side) of the wheel’s centerline.
Wheel Selection for Project Boosted Coyote
With all this in mind, Ivan decided on Forgestar’s CF10 wheels finished in Gunmetal, sized 20×9.5-inches with a 29mm offset up front and 20×11-inches with 56mm offset in the rear.
The CF10 is a monoblock wheel created from Forgestar’s Rotary Forged Flow forming process.
According to Forestar, the process begins with a specially designed casting that is spun while heating the outer portion. Next, hydraulic rollers are used to form the barrel by applying heat and pressure. As the rollers extend outward on the barrel, the aluminum is stretched and compressed, changing the mechanical properties and increasing the strength of the aluminum. This process allows the final product to be lighter and stronger, with impact values similar to those of a forged rim.
The CF10 was designed for speed with 10 narrow spokes and a thin lip. It has been coated with a strong, highly weather-resistant gunmetal powder finish and features the standard five-lug pattern with a deep concave center.
Tire Selection and Sizing
“I was searching for a tire I could use for daily driving. I wanted something that would give me great dry weather traction but also handle a bit of water if I got stuck in the rain,” Ivan said. Other features on his wishlist included the ability to perform at roll racing events, take on back roads, put up with spirited street driving, and be able to handle all that a 700 to 1000-wheel-horsepower car can throw at it.
“I have been a Toyo customer probably for as long as I have had a license to drive,” Ivan said, adding he trusts the brand and its products. Consequently, Ivan chose to wrap the CF10 wheels in Toyo Tires Proxes R888R,285/35ZR20 in front with 305/35ZR20 in the rear.
The R888R is an evolution of the race-winning Proxes R888, which Toyo says delivers faster lap times and better dry handling than its predecessor.
What separates the R888R from the R888 is its new tread design and an improved contact patch that has been optimized to improve dry traction in braking, acceleration, and cornering.
The contact patch comes with massive tread blocks on the outside tread which maximize lateral grip for improved cornering while the wide center rib improves directional stability and precise steering response.
Lastly, the R888R consists of a high-grip race compound that allows the tire to reach its optimal operating temperature quickly and provides consistent performance.
“The tires make this car so much fun to drive. They inspire confidence, even with how heavy this 2015 Mustang is,” Ivan said after participating in a local autocross event. He added that he gets compliments on the wheels, “at the gas station, car shows, the track. The finish is the next level, and the design complements the car so well.”