It is not recommended to put two different sized tires on your car for several important reasons related to safety, performance, and legality:

Safety Concerns:

  1. Handling and Stability: Different sized tires can affect the handling characteristics of your vehicle. Mismatched tires can lead to unpredictable steering responses, especially during emergency maneuvers.
  2. Braking Performance: Variations in tire sizes can impact braking distances and effectiveness, potentially compromising safety in critical situations.

Mechanical Issues:

  1. Transmission and Differential Strain: If the tires have different circumferences, it can cause strain on the transmission and differential components, potentially leading to premature wear or mechanical issues.
  2. Traction and Stability Control: Vehicles with traction control or stability control systems rely on consistent tire sizes and characteristics to operate effectively. Mismatched tires can interfere with these systems.

Tire Wear and Longevity:

  1. Uneven Wear: Different sized tires can wear unevenly, affecting tire longevity and requiring more frequent replacements.

Legal and Warranty Considerations:

  1. Legal Compliance: Some jurisdictions have regulations regarding tire size and type. Using mismatched tires may not comply with local laws and could result in legal consequences.
  2. Manufacturer Warranty: Using tires that are not recommended by the vehicle manufacturer may void warranty coverage for related components.

What to Do Instead:

  • Replace Tires in Pairs: It's generally recommended to replace tires in pairs (either both front or both rear tires) to maintain balanced handling and performance.
  • Consult Manufacturer Recommendations: Refer to your vehicle’s owner’s manual or consult with a qualified tire professional to determine the correct tire size and type for your vehicle.
  • Maintain Consistency: Stick to using tires that match in size, type, and speed rating to ensure optimal performance, safety, and longevity.

Using two different sized tires on your car is not advisable due to potential safety risks, mechanical issues, and legal considerations. It's essential to follow manufacturer recommendations and ensure that all tires on your vehicle are properly matched for optimal performance and safety.