Biggest Tire To Fit 1990 Geo Tracker

The Biggest Tires You Can Fit on Your 1990 Geo Tracker: A Comprehensive Guide

The 1990 Geo Tracker, a compact and capable SUV, offers off-road adventure potential that can be significantly enhanced with larger tires. However, simply slapping on the biggest tires you can find is a recipe for disaster. This guide delves into the complexities of tire sizing for your 1990 Geo Tracker, providing you with the information you need to make informed choices, ensuring both performance and safety. We'll explore factors like wheel offset, lift kits, and the potential implications of exceeding factory specifications. Understanding these crucial aspects will help you determine the biggest tires you can safely and effectively mount on your classic Geo Tracker.

Understanding Tire Sizing and Terminology:

Before we dive into specific tire sizes for your 1990 Geo Tracker, let's clarify some essential terminology. Tire sizes are expressed using a series of numbers and letters, for example, 205/70R15. Let's break it down:

• 205: This is the tire's width in millimeters. A higher number indicates a wider tire.
• 70: This is the aspect ratio, representing the tire's sidewall height as a percentage of its width. A 70 aspect ratio means the sidewall height is 70% of the 205mm width.
• R: This indicates a radial tire construction, the most common type used today.
• 15: This is the wheel diameter in inches. This is crucial, as it dictates the size of rim you'll need.

Factory Tire Size and Limitations:

The 1990 Geo Tracker typically came equipped with smaller tires, often in the range of 185/80R14 or 195/75R15. These sizes were chosen to balance fuel efficiency, on-road handling, and ground clearance. However, many owners seek to increase the vehicle's off-road capabilities by fitting larger tires. This is where the challenges begin.

Factors Limiting Tire Size:

Several factors significantly restrict the size of tires you can fit onto your 1990 Geo Tracker without modifications:

• Wheel Well Clearance: The space within the wheel wells dictates the maximum tire diameter you can accommodate. Larger tires will rub against the fenders, suspension components, or body panels if they exceed this clearance. This is the most significant limiting factor.

• Suspension Geometry: Your Geo Tracker's suspension geometry plays a crucial role. Larger tires can alter the suspension's natural articulation and affect handling, ride comfort, and potentially cause premature wear and tear on components.

• Steering Geometry: Larger tires can increase the turning radius and potentially interfere with the steering linkage or other steering components.

• Brake Caliper Clearance: In some cases, larger tires may rub against the brake calipers, requiring modifications or the use of different brake components.

• Drivetrain: Depending on the drivetrain (2WD or 4WD), certain tire sizes might put added strain on components like axles, differentials, and the transfer case.

Modifying Your Geo Tracker for Larger Tires:

To fit larger tires than the factory specifications, you'll likely need to make modifications. The most common methods include:

• Body Lift: This involves raising the entire body of the vehicle relative to the chassis. This increases wheel well clearance, allowing for larger tires. However, body lifts can sometimes compromise the vehicle's structural integrity if not done correctly by professionals.

• Suspension Lift: A suspension lift raises the chassis of the vehicle, providing more ground clearance and allowing for larger tires. This is generally considered a more robust modification than a body lift. Different lift kits offer various heights, ranging from modest increases to significant gains in ground clearance. This also affects the suspension geometry, potentially requiring upgrades to shocks and other components.

• Wheel Spacers: Wheel spacers increase the distance between the wheel and the hub, allowing for wider tires and potentially improved track width. However, using spacers without considering their impact on the suspension and wheel bearings can negatively affect handling and safety.

• Fender Flares: These extend the wheel wells, providing additional clearance for wider tires, thus reducing rubbing.

• Trimming: Carefully trimming the wheel wells or other areas of the body can increase clearance for larger tires. However, improper trimming can weaken the body's structural integrity, so caution is advised.

Recommended Tire Sizes and Modifications:

Determining the absolute biggest tire size without compromising safety and performance requires a careful assessment of your specific Geo Tracker and the modifications you are willing to undertake. However, some commonly mentioned sizes and their associated modifications include:

• 215/75R15: This size may fit with minimal modifications such as fender trimming. It offers a modest increase in ground clearance and tire footprint.

• 235/75R15: This size often requires a lift kit (2-inch or more) and likely fender trimming or flares to avoid rubbing. This offers a significant improvement in ground clearance and off-road traction.

• 30x9.5R15: This size is often seen on modified Geo Trackers and usually needs a significant lift kit (3-4 inches or more), potentially including modifications to the suspension components and extensive fender trimming or flares.

Important Considerations:

• Gear Ratio: Fitting significantly larger tires changes the effective gear ratio of your Geo Tracker. Larger tires increase the rolling circumference, meaning your engine will need to work harder to achieve the same speed. This may require adjusting the gearing or considering a different differential gear ratio.

• Speedometer Calibration: Larger tires will affect the accuracy of your speedometer and odometer. You may need a speedometer calibrator or recalibration to ensure accurate readings.

• Professional Installation: Installing larger tires and making any necessary modifications is best left to experienced mechanics. Improper modifications can lead to safety hazards.

Choosing the Right Tires:

Beyond the size, selecting the correct tire type is equally crucial. Consider your primary use case:

• All-Terrain Tires (AT): Offer a good balance between on-road comfort and off-road capability. A solid choice for those who use their Geo Tracker for both commuting and light off-roading.

• Mud-Terrain Tires (MT): Specifically designed for extreme off-road conditions, offering superior traction in mud, sand, and rocks. However, they tend to be noisier and have a harsher ride on paved roads.

Conclusion:

Finding the biggest tire that fits your 1990 Geo Tracker involves careful consideration of several factors. While the desire for increased ground clearance and off-road capabilities is understandable, prioritizing safety and maintaining the vehicle's structural integrity are paramount. Thorough research, professional guidance, and a realistic assessment of your needs and modifications are essential before undertaking any changes. Remember, a gradual approach, starting with smaller increases in tire size and assessing the results, is a safer and more informed way to achieve your desired outcome. Always prioritize safety and consult with experienced mechanics to ensure your modifications are carried out correctly. The goal is to enhance your Geo Tracker's capabilities while maintaining its reliability and your safety on and off the road.