Understanding Tire Size Numbers (What Do They Mean?)

Ever stare at a tire sidewall and see "225/65R17" and wonder what it means? Here's the breakdown.

Breaking Down 225/65R17

225 = Tire width in millimeters
65 = Aspect ratio (sidewall height as % of width)
R = Radial construction
17 = Wheel diameter in inches

Why It Matters

Wrong tire size = speedometer errors, rubbing, poor handling, or even safety issues. Always match OEM specs or consult a tire pro.

Plus Sizing (Bigger Wheels)

Want 18-inch wheels on a car that came with 17s? You need lower-profile tires to keep the overall diameter the same. Example: 225/65R17 → 225/55R18. Use a tire size calculator.

Load Index & Speed Rating

After the size code, you'll see something like "102H". 102 = load index (1,874 lbs per tire). H = speed rating (130 mph max). Match or exceed OEM ratings.