Here's why:
* Tire Size: The crucial factor isn't just the rim diameter (17" or 18"), but also the tire's overall diameter and width. Simply putting a larger rim doesn't automatically mean the overall wheel and tire diameter will remain the same. If the overall diameter changes significantly, it can affect your speedometer accuracy, your car's handling, and potentially damage your transmission or other components.
* Offset: The wheel offset (how far the wheel mounting surface is from the centerline of the wheel) is critical. The wrong offset can cause rubbing against the suspension, brakes, or body. 18-inch rims often have different offset options than 17-inch rims, making it more likely to cause rubbing issues.
* Backspacing: Similar to offset, backspacing (the distance from the mounting surface to the back of the wheel) affects fitment. Incorrect backspacing can lead to interference.
To determine if 17" or 18" rims will fit, you NEED to:
1. Check your owner's manual: It may list acceptable rim and tire sizes.
2. Find the specifications of the wheels you're considering: Look for the diameter, width, offset, and backspacing.
3. Use a wheel fitment guide: Several websites specialize in helping you find compatible wheels for your car model. These sites usually ask for your year, make, and model, allowing you to input the wheel specifications and check for potential clearance issues.
4. Consider a professional consultation: A tire shop or automotive specialist can provide personalized advice based on your specific car and the wheels you're interested in. They can also check for clearance issues.
In short: While 17-inch rims are more likely to fit without issues, 18-inch rims are not impossible, but require much more careful research and planning to avoid problems. Don't just assume they'll fit based on diameter alone.
