Big Wheels Can Present Big Problems

What those 22-inch wheels mean for your car's performance.
By Mike Bumbeck, DriverSide Contributor
Upsized Downs
A sentence or two uttered during the Lincoln MKS presentation outlining the extensive suspension development required to support use of the optional 20-inch wheels served as a valuable reminder to those thinking of throwing a set of 26-inch dubs onto their Caprice Classic. Big wheels and low profile tires may look cooler but do not necessarily improve handling. A larger wheel and tire package can actually decrease maneuverability and increase braking distances. Trend-based thinking is that, by dropping the sidewall height of the tire and increasing the diameter of a wheel, an improvement in steering response and lateral handling can be found. While this is true to a certain extent, there is a point of diminishing returns.

Low Profile
In theory, an improvement in handling comes with an upsized wheel and tire package.  Decreasing the tire aspect ratio, or the percentage of tire width to tire height, also decreases side-to-side tire flex. While crisper handling is possible with a shorter tire, the pneumatic cushion between the road and car is less effective. The difference can be as dramatic as dozing off on an overstuffed mattress or trying to get cozy with a 1/2-inch thick foam camping pad.

Unsprung Weight
Increased mass of larger wheels causes other problems. The body of the vehicle sitting atop the suspension is sprung weight. The wheels and tires are bolted to the ends of the suspension are unsprung weight. Anyone who remembers playing with a gyroscope as a kid can recall how difficult the toys were to tilt or move around once they got spinning. Unsprung weight like 26-inch spinners can overwhelm the ability of a suspension to maintain vehicle control. Forged racing wheels are light. Diamond encrusted dubs are not.

Rotating Mass
Big wheels want to keep on turning. Added rotating mass of bigger wheels can overwhelm brakes designed for smaller diameter and usually lighter wheels. Consider a brake and suspension upgrade if rolling into the donk or dub zone is the plan. As did the team behind the Lincoln MKS, engineers submit a vehicle to long hours of development and testing to determine the best wheel and tire combination. Suspension and brake system are designed for the wheels and tires the factory bolts on. Anything else is style-based guesswork.


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