Are there different size tires?

Tires come in many sizes; the right size depends on your vehicle, wheel, and intended use. Using the correct size is essential for safety, performance, and compliance with manufacturer guidance.

Understanding tire sizes starts with how the markings are written, how regional sizing systems differ, and what you should consider if you’re thinking about switching to a different size. This article breaks down those basics and offers practical guidance for readers who want to make informed tire choices.

Understanding tire size basics

Reading sidewall codes

To decode common tire size markings, look for numbers and letters that describe width, height, construction, and wheel diameter. Here is what those elements typically represent on a passenger vehicle tire:

• Width: the distance across the tread in millimeters (example: 205).


• Aspect ratio: the sidewall height as a percentage of the width (example: 55).


• Construction and wheel diameter: the letter R indicates radial construction and the wheel diameter in inches (example: R16).


• Prefix letters: P denotes a passenger car tire, LT indicates a light-truck tire, and T can designate a temporary spare.

In short, the numbers and letters together describe how wide the tire is, how tall the sidewall is, and what size wheel it fits, along with the vehicle type and construction.

Regional sizing standards and compatibility

Metric vs inch-based sizing

There are two main sizing conventions used around the world. The metric (ETRTO) system is common in Europe and much of the world, while the US/Canada system often uses prefixes like P or LT and reports wheel diameter in inches. Here are representative examples to illustrate the difference:

• ETRTO example: 205/55R16 — width in millimeters, aspect ratio as a percentage, radial construction, 16-inch wheel.


• US sizing example: P205/65R15 or LT245/75R16 — begins with a vehicle-type prefix (P or LT) and uses similar width/ratio/diameter notation with an inch-based wheel diameter.

Different regions use these conventions, which is why tires that look similar on paper may not be approved for certain vehicles or wheels. Always verify compatibility with your vehicle’s specifications and local regulations.

Choosing the right size for your vehicle

Practical guidelines for changing sizes

If you’re considering a size change, follow these checks to minimize risk and ensure proper performance:

• Consult the owner's manual or the door jamb placard for approved sizes, load ratings, and speed ratings.


• Use a tire size calculator or consult a tire professional to compare overall diameter and potential speedometer or odometer changes.


• Ensure the new size maintains a similar rolling radius and load rating, and that there is enough clearance for suspension, brakes, and steering components.

Keep in mind that changing the overall diameter by more than about 3% can affect speedometer accuracy, gearing, ride quality, fuel economy, and traction control systems. When in doubt, stick to the manufacturer-recommended sizes or seek guidance from a qualified tire technician.

Summary

Yes, there are many tire sizes, and they vary by vehicle type, wheel dimensions, and region. Tire size is specified by width, aspect ratio, construction, and wheel diameter, with regional conventions (ETRTO vs US) influencing how sizes are labeled. Before changing tire sizes, verify compatibility with your vehicle’s specifications, understand the potential effects on accuracy and performance, and consult a tire professional if needed. Matching the correct size helps ensure safety, handling, and reliability on the road.

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. 

Can I go from 225 to 235 tires?

Yes, you can likely go from 225 to 235 tires, but you must ensure the new tires are compatible with your existing rims and check your vehicle's specifications, as the change can affect speedometer accuracy, fuel economy, and vehicle handling. The recommended maximum change in tire size is about 3% to avoid potential issues. It is best to consult with a professional mechanic to confirm compatibility and ensure safety before making the switch. 
Before you switch

• Check your rims: Make sure your rims are wide enough to safely accommodate the 235-millimeter tires. The rim width can be a limiting factor. 
• Consult the experts: A professional mechanic can tell you if the size change is safe and compatible with your specific vehicle. 
• Review insurance and warranty: Check with your insurance company, as a change in tire size may be considered a modification that could potentially void your warranty. 

This video explains the factors to consider before switching from 225 to 235 tires: 54sTire BloggerYouTube · Oct 8, 2024
Potential impacts of the change

• Speedometer and odometer: Your speedometer will likely read slightly higher than your actual speed, and your odometer may record slightly more mileage. You may need to adjust your speed or get a recalibration. 
• Vehicle performance: A wider tire can affect handling, steering, and braking. It could also increase wear on your transmission, axles, and other drivetrain components. 
• Tire wear: The new tires may wear unevenly if they are not the correct size for your rims. 
• Fuel economy: A wider tire can potentially decrease your vehicle's fuel efficiency. 
• Clearance: Depending on your vehicle's design, the wider tires could rub against the wheel arch when you are steering or cornering. 

You can watch this video to learn how tire size affects a vehicle's performance: 59sAutoMoto RatingsYouTube · Oct 4, 2025

Are there different sizes of tires?

There are many different sizes of tires, and different sized tires can be used on the same rim, as long as the middle of the tire is the correct size. A common change is to increase the size of the rims.

Can I go from 265 to 245 tires?

Yes, you can replace a 265 tire with a 245 tire, but you must also ensure the aspect ratio and wheel diameter are correct for the vehicle. You should also consider that the new tires are about 20mm narrower and may affect your speedometer reading and fuel efficiency. It's best to buy all four tires to maintain consistency, especially since switching between sizes can put extra strain on your vehicle's drivetrain and suspension systems. 
Things to consider

• Tire width: The 245 is 20mm narrower than the 265 tire, which could affect grip and stability. 
• Aspect ratio: The second number in the tire size (e.g., the '65' in 245/65R17) is a percentage of the width. You must use a compatible aspect ratio to maintain similar overall tire height. 
• Wheel width: A 245 tire is typically designed for a narrower wheel than a 265 tire. Ensure the wheel width is within the recommended range for a 245 tire. 
• Speedometer and odometer: A 245 tire is slightly smaller in diameter, which will make your speedometer read slightly faster than your actual speed. 
• Clearance: A narrower tire is less likely to rub against the wheel wells, but you should still check for adequate clearance. 
• Tire replacement: It is always best to replace all four tires to ensure consistent handling, traction, and wear. Replacing tires in pairs can cause an adverse effect on your vehicle's suspension, gear ratios, and transmission. 
• Tire type: Ensure your new tires are the same type and have a speed and load rating that meets or exceeds the original tires' specifications. 
• Professional advice: Consult a tire professional or your vehicle's owner's manual to confirm the correct tire size and specifications for your vehicle.