How to Find Your Tire Size for Your Car
Using the correct tire size for your car is crucial to ensuring safe driving practices. Incorrect tire sizes can compromise your ability to brake, impact your traction, and even reduce fuel efficiency.
Before purchasing new tires, use our guide to determine the right tire size for your vehicle.
Not sure about your tire size? Talk to our tire experts at Hooper’s Tire Outlet to determine which tire is right for your car!
How to Find the Right Tire Size
Check Your Vehicle Manual
Read Your Tire Markings
Use a Tire Calculator
1. Check Your Vehicle Manual for Your Tire Size
Vehicles are engineered with a specific tire size to match the car’s index load, speedometer readings, and safety measures. You can find the manufacturer’s recommended tire size in the driver’s or passenger's door jam or as a window sticker, including the original tire size and tire pressure recommendations.
Credit: Vin’s Labels
If your car lacks a door jamb sticker like the image above, check your vehicle’s manual online or search for an official resource.
2. Read Your Tire Markings
You can also find your vehicle’s tire size by reading the tire markings on your current tire (assuming the tire size is within the manufacturer’s recommended specs). Tire size markings follow international standards to ensure compatibility across different vehicles and brands.
Let’s break down this example: P185/75R14
Vehicle Type (P): The first letter is the vehicle prefix, which designates the type of vehicle. The most common vehicle prefixes include:
P = Passenger Car (e.g., SUVs, light-duty pickups, station wagons)
T = Temporary Spare
LT = Light Truck
ST = Trailer
Tire Width (185): The larger number before the slash is the tire width in millimeters. Generally, wider tires offer more grip on the road, though it's best to ensure the width is within your vehicle’s recommended tire specs.
Aspect Ratio (75): This percentage represents the height of the tire sidewall relative to the tire width. A higher aspect ratio can improve ride comfort but should be within the recommended vehicle specs.
Tire Construction (R): Tire construction is typically the second letter on the tire marking. The most common tire construction types include:
R = Radial-Ply Tires
D = Diagonal-Ply (or Biased-Ply) Tires, commonly used for trucks and trailers
B = Bias-Belt Construction is the same as biased-ply but includes an additional security belt to reinforce the tire
Rim Diameter (14): The final number indicates the diameter of the wheel in inches. Regardless of changes to the other tire markings, you must match the rim diameter number to ensure the tire fits properly.
For a visual breakdown of the tire, refer to this video from Autobytel.
3. Use a Tire Calculator to Find Compatible Tires
Once you know your current tire size, you can shop for options in the suggested size or use a tire calculator to find compatible tires for your vehicle.
Tire calculators allow you to compare multiple tire sizes to understand the differences as percentages. Some tire calculators will show how driving speed changes at different velocities. The general rules of thumb are:
Stay within a 3% difference when comparing the tire diameter (tire height) to the recommended tire specs.
Keep the rim diameter the same.
If you increase tire width by 1 increment, then decrease the aspect ratio by 1 increment.
Understanding Tire Sizes
With so many tires on the market, it can be difficult to find the correct tire size for your vehicle. By using our guide, you can quickly identify the recommended tire specs through your car manual or existing tires and purchase compatible tire models.
Always prioritize matching the correct tire size to your vehicle to avoid issues with handling, braking, and fuel efficiency.
Looking to replace your tires?
Bring your vehicle to Hooper’s Tire Outlet in Rochester, NY, or Syracuse, NY, and explore our tire services! You’re sure to find a high-quality used tire to fit your car and budget! We may also offer a close or optional size if your exact size is not in stock.