Nominal geometry, clearly compared

See what a tire-size change actually changes.

Compare diameter, sidewall, nominal radius change, wheel revolutions, and estimated speedometer effect. Everything runs in this page—no uploads, cookies, or tracking.

01 / COMPARE

Enter two passenger-metric sizes

Accepted: 205/55R16, P205/55R16, or 205/55ZR16. Load and speed suffixes are intentionally refused.

03 / BOUNDARY

Geometry is not fitment.

TireShift does not evaluate wheel width, offset, bolt pattern, brake or suspension clearance, rubbing, load rating, speed rating, pressure, ABS behavior, legality, or manufacturer approval.

Published size is nominal. Actual dimensions and loaded rolling radius vary by tire, wheel, pressure, load, wear, and construction. The threshold is a comparison heuristic—not a safety rule.