Is it OK to have one tire different size?
In everyday driving, some car owners wonder if a single tire can be a different size from the others. The concise answer: it’s generally not advisable, especially on vehicles with all-wheel drive. The safest route is to have all four tires match in size (and ideally in tread and brand) to maintain predictable handling and prevent drivetrain stress. This article breaks down why size differences matter, where exceptions might apply, and how to proceed safely.
How tire size differences affect your vehicle
Differences in tire size create inconsistencies in how each wheel rolls, which can impact steering, braking, and stability. This is especially important on modern cars that rely on sensors and electronically controlled systems that assume uniform tire behavior.
Below are the main safety and performance concerns to consider if you plan to run a different-sized tire on one wheel.
- Drivetrain and traction issues on all-wheel-drive (AWD) or four-wheel-drive (4WD) systems can occur if the tires don’t share the same rolling diameter, potentially causing binding, increased wear, or even drivetrain damage over time.
- Handling, steering response, and stability can be compromised because one corner of the car behaves differently from the others, especially during cornering or emergency maneuvers.
- ABS, traction control, and electronic stability programs rely on consistent wheel speeds. A mismatched tire can trigger false readings or reduce system effectiveness.
- Tire wear, ride comfort, and noise levels can become uneven, shortening tire life and affecting ride quality for the passengers.
- Legal, insurance, and warranty considerations may apply. Some manufacturers and insurers expect all four tires to be the same size and specification for safe operation.
In short, mismatched tire sizes on a single wheel can introduce risk and should be avoided unless you have a clear, professional plan to manage the difference and understand the vehicle’s specifications.
AWD, 4WD and front/rear axle considerations
All-wheel-drive and some performance-oriented vehicles are particularly sensitive to wheel-size differences. The rolling diameter—the actual distance traveled in one wheel revolution—needs to be consistent across all four corners to prevent drivetrain stress and inaccurate sensor readings.
Rolling diameter and drivetrain stress
Even small differences in overall diameter (the tire’s height, width, and aspect ratio) can create unequal torque delivery and differential loading. For many AWD systems, manufacturers recommend a maximum diameter variance of a few percent between tires. Exceeding this can lead to slip, binding, or accelerated wear on the center or rear driveline components.
- Prefer matching tires on all four corners. If one tire must differ, the difference should be minimized and within the vehicle manufacturer’s specified tolerance.
- If you are replacing only two tires (on the same axle) you should replace with tires of the same size, speed rating, and similar tread pattern to preserve handling and compensation in the system.
- Some vehicles explicitly prohibit mismatched tires on AWD systems; in such cases, a mismatch could void warranties or complicate insurance claims after an incident.
When in doubt, consult your vehicle’s owner manual or a certified tire professional about tolerances and the best course of action for your specific model.
What to do if you already have a mismatch
If you discover you have a tire that’s a different size than the others, take careful, immediate steps to limit risk and plan a proper fix.
- Limit driving and avoid high-speed or aggressive maneuvers until you can replace the tire with a correctly sized one.
- Check the other three tires for wear and ensure they are the same size, brand, and model where possible.
- Consult a tire professional or your dealer about whether you can move the mismatched tire to a non-drive axle (if allowed by the vehicle and local regulations) or whether it must be replaced to restore uniformity.
- Replace the mismatched tire with the same size, speed rating, load index, and tread pattern as the rest of the set to restore balanced handling.
- After replacement, have the alignment and wheel balance checked to ensure there are no residual handling issues.
In practice, the safest path is to install a full set of matching tires or at least replace the mismatched tire with one that matches the others in diameter and specifications, as recommended by a professional.
Choosing replacements and preventing future mismatches
To prevent issues before they arise, follow these guidelines when selecting new tires or keeping a set in rotation.
- Always aim for identical tire sizes on all four wheels (same brand, model, tread pattern, and wear level) when possible.
- If you must mix sizes temporarily, keep the difference to a minimum and verify that your vehicle supports the configuration without compromising safety systems.
- Match overall diameter within manufacturer tolerance (typically within a few percent, often 1-2%, and rarely more than 3%).
- Check vehicle documentation and speak with a professional about AWD/4WD implications and required maintenance procedures.
- Consider selling or trading any non-matching tire and investing in a complete, balanced four-tire setup for optimal performance and longevity.
By planning replacements carefully and adhering to the vehicle’s specifications, you reduce the risk of drivetrain wear, handling surprises, and potential insurance or warranty concerns.
Summary
Having one tire that’s a different size from the others is not recommended for most vehicles, especially those with AWD or sensitive electronic stability systems. The safest approach is to run four matching tires or, at minimum, ensure any size differences stay within the manufacturer’s specified tolerances and are professionally evaluated. Regular maintenance, proper matching, and guidance from a tire professional help preserve safety, handling, and longevity of your tires and drivetrain.
