What is the size of my wheels?
There isn’t a single universal number. Wheel size depends on what you’re asking about—car wheels or bicycle wheels. For cars, the size is the wheel diameter in inches (often shown on the tire sidewall and on a vehicle placard). For bicycles, size is described by the wheel diameter in inches or by the ISO bead seat diameter in millimeters (most commonly 622 mm for 700c). To determine yours, check the tire markings and the relevant manuals or labels, or measure carefully.
Car wheels: how to determine the size
These are the standard methods used to identify the wheel size on most passenger cars.
- Check the tire sidewall. A typical tire size like P205/55R16 ends with a number that matches the wheel diameter in inches (here, 16 inches). The letters and numbers describe width and aspect ratio; the last number indicates the wheel size the tire is designed to fit.
- Look at the driver’s door jamb placard or the owner’s manual for the OEM wheel/tire size recommended by the manufacturer. This is the official specification for your vehicle.
- Inspect the wheel itself for stamped measurements such as 15x6J (diameter 15 inches, width 6 inches) and offset values like ET42. The diameter stamp helps you verify the wheel’s size, while the offset affects fitment.
- If you remove the tire, measure the rim diameter directly across the center from bead seat to bead seat, or consult a service manual for the correct measurement. This confirms the actual wheel diameter when necessary.
These sources typically align: the tire sidewall indicates the practical diameter, while the placard and manual confirm the manufacturer’s recommended size and fitment.
Compatibility and safety considerations
When selecting or changing wheels, consider clearance with fenders and suspension, brake type and diameter, bolt pattern, and wheel offset. Using a size outside the manufacturer’s recommendation can affect handling, safety, and sensor performance such as ABS and speedometer accuracy.
Bicycle wheels: how to determine the size
These are the common methods for identifying bicycle wheel sizes, which follow different conventions than motor vehicles.
- Read the tire sidewall. Road tires often show a label like 700x23c, while mountain bike tires show widths in inches or millimeters. The key size for wheel compatibility is the bead seat diameter (BSD), often listed as an ISO number such as 622.
- Check the rim or wheel labeling. Common diameters include 622 mm (frequently marketed as 700c for road bikes), 584 mm (27.5" MTB), and 559 mm (26" MTB). The number corresponds to the bead seat diameter, not the tire width.
- Understand ISO/ETRTO sizing. A typical tire-rim pairing is described as 47-622 (47 mm width, 622 mm BSD). This precise system ensures tires fit the rim correctly.
- Consider the bike type and braking system. Road bikes typically use 622 mm rims with rim brakes, while many mountain bikes use 584 mm or 622 mm rims with disc brakes or different hub spacings. Verify compatibility when upgrading wheels or tires.
For precise tire–rim compatibility, rely on ISO/ETRTO measurements rather than approximate inch-based labels alone.
Summary
In short, car wheel size is defined by the wheel diameter in inches (as indicated on the tire and in the vehicle’s labeling), while bicycle wheel size is defined by the ISO bead seat diameter in millimeters (with common values such as 622 mm for 700c, 584 mm for 27.5", and 559 mm for 26"). To determine your exact size, read tire sidewall markings and check the vehicle’s placard or bike specifications; when in doubt, consult a professional to ensure proper fitment and safety. If you share your specific vehicle or bike details, I can help identify the exact wheel size.
What does 4.80 4.00 mean?
The numbers 4.80/4.00-8 read like this: 4.80" is the tire width, 4.00" is the tire section height (from the inside of the donut hole to the outside) and the 8" is the wheel diameter. Finally, the numbers 4.80-8 read like this: 4.80" is the tire width and "8 is the wheel diameter.
How do I tell what size wheels I have?
First, start with the wheel size for your vehicle. You can find that on the sidewall of the tires on your original wheels or the inside frame of the driver's door. Check out Tire Size Explained (Reading the Sidewall) for more. The wheel diameter (in inches or millimeters) is the fifth set of numbers and letters.
Does R17 mean 17 inches?
R stands for radial construction which refers to how the tires are made. 17 is the rim diameter in inches of the wheel from one end to the other.
What size are my stock rims?
To find out the width of your stock wheel, you must look at the back side of the rim itself. Imprinted on a spoke of the OEM wheel is a number, such as 16x7. The “16” refers to the diameter, another way to discover this element, and the “7” refers to the rim's width.
