Tire Size Comparison Calculator

Yes — within limits. The general rule is to keep overall diameter within ±3% of the OEM size. Going wider improves grip but can rub fenders or suspension at full lock; going narrower improves fuel economy slightly. Plus-sizing (larger rim, lower-profile tire) preserves diameter but stiffens ride. Always confirm load index and speed rating meet or exceed the original.

Three numbers, in order: 225 = section width in millimeters (sidewall to sidewall). 45 = aspect ratio — sidewall height as a percentage of width (45% of 225 mm = 101 mm sidewall). R = radial construction (the standard for passenger cars). 17 = wheel diameter in inches. The trailing letters and numbers (e.g., 94H) encode load index and speed rating.

Yes, modestly. Larger and wider tires weigh more (rotating mass), have more rolling resistance, and create more aerodynamic drag. A typical plus-2 upgrade (e.g., 16 → 18) can drop fuel economy by 1–3 mpg. Going to a much taller tire on a truck (e.g., for off-road) can drop economy by 10% or more.

Plus-sizing means increasing rim diameter while decreasing tire aspect ratio to keep overall diameter the same. Plus-one = 1 inch larger rim (e.g., 17 → 18); plus-two = 2 inches larger. The benefit is sharper steering response and a more aggressive look; the trade-off is harsher ride and higher rim damage risk on potholes.

Beyond the size, the sidewall shows: load index (a number like 94 = 1,477 lb max load per tire), speed rating (a letter like H = 130 mph max), DOT code (manufacturing date — last 4 digits are week/year, e.g., 2823 = week 28 of 2023), and treadwear/traction/temperature ratings. UTQG numbers like 500AA mean treadwear grade 500, A-traction, A-temp.