Can the Wrong Size Tire Damage Your Car?

A ton of engineering, research and development goes into selecting the original equipment tire size for a vehicle.

Performance engineers have a keen interest in tire size because it has a direct influence on a vehicle’s driving dynamics. Vehicle body and chassis engineers establish limitations for tire size due to the arrangement of suspension components, body panels and fender liners, and a wide variety of other parts.

Nevertheless, the allure of altering tire size to enhance certain performances, or just for aesthetic purposes, is strong for many driving enthusiasts.

Unfortunately, altering the tire size of a vehicle without thorough and careful consideration is a decision that can really bite. Fitting the wrong tire size can cause damage to a vehicle, and is a real safety hazard as well.

Here’s a rundown of considerations and potential hazards associated with an ill-judged tire size change.

Changing the tire section width

Where to find your tire width

Upgrading the tire width, also called the contact patch or footprint of a tire, has potential performance upsides for on- and off-road vehicles alike. And it’s not uncommon that original equipment wheels can accommodate a wider tire size than stock.

However, fitment of a tire that’s too wide can result in contact with various vehicle components, and vehicle damage ranging from minor to significant is possible.

• Fender liner contact: The plastic lining that covers the inside of the wheel well is the most common contact point of an aggressive, aftermarket tire fitment. Whether under certain suspension compression conditions or with significant steering angle, some “rubbing” of the fender liner can occur. While not advisable or recommended, an occasional light touch of the fender liner is considered acceptable in certain performance driving circles.

• Vehicle body contact: Whereas the fender liner is somewhat malleable, the vehicle body panels that adjoin with the wheel wells and fender liners are not. Contact with these panels should be strictly avoided as vehicle body damage and/or tire damage are likely. (More on the tire damage hazard below.)

• Suspension component contact: Contact with the strut and spring is possible if the tire width is sufficient to reach these components under certain compression conditions. A tire bumping these components during any driving conditions must be strictly avoided. Suspension damage and a potentially severe influence on vehicle drivability can result.

• Electrical lines and components: These are generally kept well out of reach of spinning tires, but depending upon the aggressiveness of the aftermarket tire fitment they could be reached. The ramifications of tire tread “catching” any electrical lines or components are self-evident.

• Fuel system component contact: There’s a lot of vital mechanical activity that occurs just behind the fender liners of many vehicles. For example, fuel system components and lines running fore and aft of the vehicle are sometimes routed in and around the wheel wells. Various sensors and electronics can also be housed inside the wheel wells.

The fender liner acts as a barrier and protection against direct contact damage, but excessive bumping and pressure sent through the fender liner could cause hazardous damage to these components.

Changing the aspect ratio/side profile of the tire

Adding tire sidewall is another common tire size adjustment, especially from an aesthetic standpoint on trucks and SUVs. The taller sidewall profile adds an element of muscularity to the side view of the wheel, and the vehicle as a whole. Even a small bump in vehicle ride height can be achieved with an aspect ratio upsize.

As with an increase in tire width, increasing the sidewall height of the tire is not without potential hazards.

Interior suspension components are generally not in the cross hairs, but the fender liner and connecting body panels above, in front of, and behind the tire can be contact points.

All-Terrain or Mud-Terrain tire tread can really do a number on these areas if contact is made at speed.

If upsizing the aspect ratio of your tires, thorough clearance measurements throughout the range of suspension travel, and from lock to lock on the steering wheel should be gathered.

The tire damage hazard

If regular tire contact is made, then it’s not just vehicle damage that could ensue – irregular tire wear, and in extreme cases, even tire structural damage can occur.

This type of tire wear can occur without the driver’s awareness. If you upsize your tires and are pushing space limitations, a periodic check for irregular “rub” tire wear should be conducted.

The long-term vehicle wear consideration

Even when all measurements check out and a tire size change will not create any visible damage, the long-term wear of certain vehicle components should be considered.

For example, an increase in tire size can cause accelerated drivetrain wear. According to AAMCO Colorado:

“The increased size causes the tires to rotate slower to cover the same amount of ground. It will take more power to accelerate because your drivetrain’s mechanical advantage has been decreased.  If you are running an automotive transmission this can cause some serious strain depending on the current gear ratio if you choose not to regear your system.”

Increased wear can also occur with the transmission, brakes, axles, CV joints, differential components, and more.

Of course, a tire size change isn’t all bad news. This information is intended to emphasize the importance of careful consideration when changing tires, and to help you avoid vehicle damage and unsafe driving conditions.

If you’re thinking about a tire size change, then consultation with a professional mechanic is highly advisable.

You can discuss your potential tire upgrade plans with us. We’re happy to weigh in and provide feedback. Give us a call at 866-961-8668.