What size tires came on?

There isn’t a universal tire size; the original equipment size depends on the vehicle’s exact make, model, year, and trim. If you share those details, I can confirm the precise OE size. In general, you’ll find the size on the door jamb placard or in the owner's manual.

This explainer breaks down how to determine the original equipment tire size, how to read common tire-size notations, and where to locate official specifications. It also covers variations you may encounter, such as different sizes for front and rear on some models, market-specific options, and spare-tire sizing.

Decoding tire size notation

What the numbers and letters indicate

The size designation on a tire encodes width, profile, construction, and fitment. Here are the common elements you’ll see and what they mean:

• Width: The first number is the tire width in millimeters (e.g., 205 mm).


• Aspect ratio: The second number is the sidewall height as a percentage of the width (e.g., 65% in 205/65R).


• Construction: The letter after the slash indicates construction type; R means radial construction (the vast majority of passenger tires).


• Wheel diameter: The number after the construction letter is the wheel diameter in inches that the tire fits (e.g., 16 inches).


• Load index and speed rating: The final part shows the tire’s performance characteristics; the load index is a number (e.g., 92) and the speed rating is a letter (e.g., H). Some sizes combine these as 92H without a space.

Understanding this notation helps you compare tires and verify that a replacement matches the vehicle’s original specifications. It also clarifies why exactly identifying the OE size from official sources matters.

Where to find the original equipment (OE) tire size

Official sources and vehicle markings

To confirm the exact original equipment size, check these official sources and the car itself:

• Tire placard on the door jamb or door frame, usually near the driver's seat. It lists the approved tire size for the vehicle and may include front/rear distinctions or spare size.


• Owner’s manual or maintenance booklet, which contains specifications for tires and wheels.


• Vehicle Identification Number (VIN) decoding via the manufacturer’s website, dealership, or authorized service portal to pull the OE build sheet.


• Factory window sticker or original sales documents for new vehicles, which specify the OE tire size used at delivery.


• Dealer or manufacturer technical documents if you cannot locate the placard or manual.

After checking these sources, you’ll have the precise OE tire size for accurate replacements. Note that some models use different sizes for front and rear, or offer market-specific options, so always verify against the exact vehicle configuration.

Summary

In short, the exact tire size that came on a vehicle depends on the specific make, model, year, and trim. To get the precise OE size, locate the tire size on the door jamb placard, consult the owner’s manual, or use VIN-based specifications from the manufacturer or dealer. Tire sizes use a standard notation that encodes width, aspect ratio, construction, wheel diameter, and load/speed ratings, which helps you compare and select appropriate replacements. If you share your vehicle details, I can look up the exact original equipment tire size for you.

Is a 275 tire the same as a 33?

No, a "275 tire" is not the same as a "33-inch tire" because the numbers represent different measurements in a tire's size. However, a specific metric size, such as a 275/60R20, can be nearly equivalent to a 33-inch diameter tire. The term "33" is a common, non-metric measurement for a tire's approximate overall diameter. 
Tire size explained

• Metric size (e.g., 275/60R20): This is a precise measurement with three parts: 
  • 275: The width of the tire in millimeters. 
  • 60: The aspect ratio, which is the height of the sidewall as a percentage of the width (60% of 275mm). 
  • R20: The radial construction and the diameter of the wheel in inches. 
• Non-metric size (e.g., 33x12.5R20): This is a common, more direct way to refer to a tire's approximate overall diameter: 
  • 33: The approximate total height of the tire in inches. 
  • 12.5: The width of the tire in inches. 
  • R20: The radial construction and the diameter of the wheel in inches. 

When they are similar

• A 275/60R20 tire is a close equivalent to a 33-inch tire, with a total diameter of approximately 33 inches. 
• Other metric sizes, like a 285/75R16, also result in a diameter close to 33 inches. 

Why it matters

• Compatibility: Always check the exact metric size of a tire to ensure it will fit your vehicle and is compatible with your suspension and wheel size.
• Speedometer accuracy: Changing your tire diameter significantly can cause your speedometer to be inaccurate. For example, larger tires will make you appear to be driving faster than you actually are. 

What size tires originally came with my car?

The original tire size for your car can be found on a sticker located on the driver's side door jamb. You can also check the owner's manual, the fuel filler door, the glove box, or the sidewall of your current tire to find this information.
 

• Driver's side door jamb: This is the most common location for the vehicle's tire information placard, which lists the correct original equipment (OE) tire size and recommended inflation pressure. 
• Owner's manual: The owner's manual contains details about your car's specifications, including the original tire size. 
• Other locations: Less common but still possible places to find the information include the inside of the gas tank hatch, the glove box, or the center console door. 
• Tire sidewall: The sidewall of the tire itself also has the size printed on it. However, if the previous owner changed the tires, the current ones may not be the original size, so the door jamb or owner's manual is a more reliable source for the OE size. 

What other size tire can I use?

You can use a different tire size, but it is critical to maintain a similar overall tire diameter, ideally within 3% of the original, to ensure safety and proper vehicle function. To find compatible sizes, check your vehicle's owner's manual or the driver's side door jamb sticker for the original tire size, and then use a tire size calculator to find alternatives with a compatible diameter, width, and aspect ratio.
 
How to choose a different tire size

• Find your current tire size: Look on the sidewall of your current tires for the size, which is a three-part number like 205/55R16. This indicates the width, aspect ratio, and rim diameter. 
• Check your owner's manual: The owner's manual will list the recommended original equipment (OE) tire sizes for your vehicle. It's also the best source for information on what is compatible with your specific vehicle. 
• Use a tire size calculator: Use an online calculator from a tire retailer to compare sizes. These tools can help you find alternative sizes that keep the overall diameter within a safe range. 
• Keep the diameter similar: The overall diameter of the new tire should be within 3% of the original size to avoid issues with your speedometer, odometer, and anti-lock brakes, as well as clearance problems. 
• Match the load and speed ratings: The new tires must have a load index and speed rating that is equal to or higher than the original tires. 
• Consider the rim width: If you change the tire width, you may also need to ensure the new tire is compatible with your rim's width. 
• Maintain equal performance: It's generally recommended that all four tires be the same size, load index, and speed rating, and that they are all either radial or non-radial construction. 

Important considerations

• Wheel well clearance: Wider or taller tires may rub against the inside of the wheel well, suspension components, or brake lines. 
• Impact on handling: Different sizes can affect how your car handles, how the speedometer reads, and even how your brakes function. 
• Professional advice: It is always a good idea to consult a professional mechanic to ensure the new tires will fit properly and safely on your vehicle. 

What is the 7 7 rule for tires?

If you leave them on too late, your winter tires will degrade quickly. So, when is the right time to swap? The rule of thumb is 7-for-7: wait until there are seven consistent days at 7 degrees Celsius. The reverse is also true for transitioning to winter.