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It goes without saying that each state enforces its own rules regarding car modifications. While some are more lenient and allow wide tires and offset wheels, others are very strict and forbid almost all forms of customization. Before modifying or moving to Missouri with a custom car, drivers should know the laws to ensure that their vehicles are street legal. This article will take a look at Missouri’s regulations and answer frequent questions regarding car modifications, particularly about tire size.
How Much Can the Tires Stick Out in Missouri?
Like many states, Missouri enforces regulations regarding the size of tires. More specifically, the total width of a vehicle needs to be less than 8 feet. In other words, as long as the vehicle doesn’t pass that threshold, it can be driven legally. However, matters get a bit more complex when it comes to fenders and mud flaps.
Does Missouri Require Fenders?
According to Missouri law, all commercial vehicles, including trucks, semis, or trailers that weigh more than twenty-four thousand pounds, must carry mud flaps in order to protect their rear wheels when operating along public highways. The purpose of this rule is to stop vehicles from throwing up debris or dirt. (Find out here what is considered a commercial vehicle in Missouri.)
If a driver wants to install bigger wheels, they’ll have to ensure that the fenders are just as wide. They must also have a clearance of between 9 and 12 inches when the vehicle is on the road.
What Is Wheel Offset?
It’s important to understand that the wheel offset also affects how much the tires stick out. Simply put, the offset is the distance from the wheel’s centerline to its mounting surface. This distance is measured in millimeters and can be negative, positive, or zero.
For example, if a driver puts a +15 mm offset wheel on their car, the tire will stick out 1 additional inch. A lower offset well will stick out farther, meaning that if the car originally had a +50 mm offset and the driver replaced it with a +25 mm offset wheel, then the tire will stick out two inches farther. Actually, most lifted trucks or low riders with wheels that stick out are due to a low offset, usually negative.
How to Choose the Right Wheel Offset?
Drivers need to install wheels with the right offset so that they don’t rub against the brake calipers, fenders, or suspension components. Additionally, depending on the offset, the wheels could stick out too much, making the vehicle illegal.
Generally speaking, front-wheel drive vehicles have a positive offset by default. Drivers who want to put wider wheels on their vehicles will need to reduce the offset. By doing so, the wheel will sit more inward and, thus, won’t extend out too far and block the fenders.
Is It Legal to Change the Wheel Offset?
In Missouri, people can adjust their wheels' offset as long as they don’t extend their tires too far. In other words, any wheel offset is 100% legal as long as it doesn’t affect the overall car width. However, a certified mechanic is the only one who can make adjustments to the wheel offset. In fact, that’s the only way to make sure that the adjustment won’t affect the car’s insurance.
Can the Wheel Offset Affect Its Alignment?
It’s worth noting that the wheel’s suspension design is unique for a specific size and offset tire combination. As a result, if a driver wants to change the offset, they will need a new alignment. The same applies if they want to replace the tires and rims with any other except the exact model and size of the original.
Final Thoughts
When buying a used car or looking to upgrade an existing one, drivers need to be aware of the local rules and regulations. Fortunately, Missouri is much more lenient when it comes to tire modifications and only enforces the bare minimum. So, as long as vehicles are not wider than 8 feet, they can be legally driven all throughout the state of Missouri. However, drivers should keep in mind that rules and regulations constantly change. Thus, checking the Missouri Revisor of Statutes for any updates or asking local mechanics is highly advisable.
For other concerns regarding the rules and regulations of operating vehicles, you may consult a truck accident lawyer in St Louis today.
We can also address questions related to other cases such as if Missouri is a fence in or fence out state.