185/55R15 vs 205/50R16
205/50R16 is taller than 185/55R15 by 4.60% — a diameter difference of 1.06″.
What changes between 185/55R15 and 205/50R16
Switching from 185/55R15 to 205/50R16 changes overall diameter by +4.60%, a taller tire by 1.06 inches. This sits in the 3–5% caution band, where rubbing at full steering lock or suspension compression becomes possible. Leveling kits or fender-liner trims are often needed on lifted trucks. Section width moves by +0.79″ (185mm → 205mm), which affects contact patch and fender-well clearance. Sidewall height shifts by +0.03″: a taller sidewall softens ride quality and adds off-road bump protection, with some loss of steering crispness. Revs per mile moves by -38, which translates directly to speedometer error — at an indicated 65 mph, actual speed becomes 68.0 mph. The swap also changes rim diameter from 15″ to 16″, meaning new wheels are required. Wheel cost typically dominates the total upsize budget.
| Spec | 185/55R15 | 205/50R16 |
|---|---|---|
| Overall diameter | 23.01″ | 24.07″ |
| Section width | 7.28″ (185 mm) | 8.07″ (205 mm) |
| Sidewall height | 4.01″ (55%) | 4.04″ (50%) |
| Rim diameter | 15″ | 16″ |
| Circumference | 72.29″ | 75.62″ |
| Revs per mile | 876 | 838 |
Interactive comparison
275/65R18 or "33" for inch aliases185/55R15
- Diameter
- 23.01″ / 584.5mm
- Section Width
- 7.28″
- Sidewall
- 4.01″ / 101.75mm
- Circumference
- 72.29″
- Revs/Mile
- 876
205/50R16
- Diameter
- 24.07″ / 611.4mm
- Section Width
- 8.07″
- Sidewall
- 4.04″ / 102.5mm
- Circumference
- 75.62″
- Revs/Mile
- 838
Speedometer & Diameter Impact
Different rim — new wheels requiredAt an indicated 60 mph, your actual speed is 62.76 mph (101 km/h). Your speedometer reads 4.60% low versus actual speed.