Rolling down the street in your SUV with 22 inch rims can be something that makes you feel like you are king of the road. Oversized rims are all the rage on all sorts of vehicles and nothing adds bling to your ride like wheels that are huge and loaded with chrome.
While you might think it makes your ride look good, and I’m not saying it doesn’t, there are a few problems that you have when you put big custom rims at each corner of your ride. The biggest problem with this type of customization has to do with what we call unsprung weight.
Anything on the vehicle or in the vehicle that exerts the force of its weight on the springs of the suspension system is sprung weight. This would be most of the vehicle, such as the body, frame, engine and transmission, or anything that is placed inside the vehicle like passengers and cargo. This is sprung weight because it is all supported by the springs, and suspension system action can control the force of this weight.
Anything that exerts the force of its weight on the tires only, and not on the springs, is unsprung weight. This is because the weight is below the springs. Things like rims and tires, steering knuckles, brake assemblies, and drive axles fall into this category. These are all items that spring action and suspension articulation cannot control.
Generally speaking the more unsprung weight a vehicle carries, the harsher the ride is. Pickup trucks and many SUV’s that are built for heavy-duty applications tend to have more unsprung weight and therefore have a ride that is not so smooth. Higher unsprung weight can also lead to handling characteristics that are undesirable. All that weight causes the wheels to bounce around more and lead to more situations where they are not firmly planted. Wheels that are not firmly planted cause poor ride quality and poor directional stability.
Oversized rims are very heavy and add a tremendous amount of unsprung weight to the vehicle. Even if the rims are made of aluminum they can still add hundreds of extra pounds, especially if you add bigger tires with the bigger rims. Many times the tires are not much bigger in diameter than the stock tires, but the section height, or the height of the sidewall, is narrower to accommodate the larger rims. This low profile tire adds to the modern, sporty look of the large rims but it further decreases ride quality.
Another common mistake when having custom rims installed relates to the overall fit of the rim and tire assembly. Obviously the tire and rim assembly must fit within the wheel arch and not be so big that it rubs on any of the body or suspension parts. In order to get some wheels to fit properly, or to provide the look that the owner of the vehicle wants, wheel spacers are added to the hub of the wheel and then the tire and rim assemblies are bolted to the spacers.
Wheel spacers can cause big problems and are actually illegal in some states because they can make the vehicle handle dangerously, and they are easy to install improperly which may cause the wheels to fall off while driving. Like the over-sized rims, they can cause excessive wear and tear on the steering and suspension components as well because suspension geometry is changed.
None of this means that you can’t customize your wheels but it just means that you need to be careful. Just because a wheel assembly bolts on doesn’t mean that it will work just fine. With so many different types of custom rims available for nearly every vehicle on the road there is no reason not to find something that will fit just right, and give you the look that you want.