Off-road enthusiasts employ countless vehicle modifications to improve performance in challenging terrain. Some of the most common off-road upgrades are lift kits, off-road tires, and body modifications. But to be street legal, these types of modifications must be within certain limits. In other words, before you invest in new tires and a lift kit, you should check to make sure your plan isn't going to exceed what the law allows. Here are some of the basics of the legal restrictions on tire sizes and lift heights.
Most states don't have specific restrictions on suspension modifications and lift limits. The states that do regulate suspension modifications typically do so for safety reasons. For example, Michigan requires that suspension modifications be done professionally with a lift kit rather than welded with scrap metal.
While longer struts and springs can increase off-road performance, they are quite expensive. To get a taller vehicle without performance suspension modifications, drivers can install spacers between the frame and body to give the vehicle a taller appearance. Raising a vehicle in this way is sometimes called a "body lift." A number of states restrict the size of the body-lift spacers. For instance, in California, these spacers can be a maximum of five inches. And Michigan prohibits the use of lifts blocks that are bigger than four inches.
Nearly every state has some form of height restriction for highway vehicles. While many states don't directly restrict suspension modifications, a vehicle owner might violate height limits by lifting a vehicle.
The laws of most states limit the distance between the vehicle's bumper or headlights and the ground. For example, some states require that a vehicle's bumper be no more than 24 inches from the ground. These limits vary state. And some states have different height limits depending on the weight of the vehicle.
It's also common for state laws to restrict the overall height and width of vehicles. For example, In Utah, passenger vehicles can't exceed 14 feet in height or 8.5 feet in width.
Another important tool for off-improved road performance is oversized, off-road tires. Generally, tire restrictions don't set a maximum tire size in inches. Most commonly, tire restrictions require that tires fit safely within the wheel well and allow the vehicle to properly turn and operate. Lots of state restrictions also limit the use of studded tires that could damage the highway. For instance, in Montana, drivers must remove studded tires outside of the winter months.
Putting large tires on a vehicle can also result in a violation of vehicle height restrictions. For example, putting 58-inch off-road tires on a truck is likely going to lift the bumper above the legal limit.