195/50R16 vs 215/40R18
215/40R18 is taller than 195/50R16 by 4.62% — a diameter difference of 1.09″.
What changes between 195/50R16 and 215/40R18
Switching from 195/50R16 to 215/40R18 changes overall diameter by +4.62%, a taller tire by 1.09 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 +0.78″ (195mm → 215mm), which affects contact patch and fender-well clearance. Sidewall height shifts by -0.45″: a shorter sidewall sharpens steering response at the cost of ride comfort and rim protection. 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 16″ to 18″, meaning new wheels are required. Wheel cost typically dominates the total upsize budget.
| Spec | 195/50R16 | 215/40R18 |
|---|---|---|
| Overall diameter | 23.68″ | 24.77″ |
| Section width | 7.68″ (195 mm) | 8.46″ (215 mm) |
| Sidewall height | 3.84″ (50%) | 3.39″ (40%) |
| Rim diameter | 16″ | 18″ |
| Circumference | 74.38″ | 77.82″ |
| Revs per mile | 852 | 814 |
Interactive comparison
275/65R18 or "33" for inch aliases195/50R16
- Diameter
- 23.68″ / 601.4mm
- Section Width
- 7.68″
- Sidewall
- 3.84″ / 97.5mm
- Circumference
- 74.38″
- Revs/Mile
- 852
215/40R18
- Diameter
- 24.77″ / 629.2mm
- Section Width
- 8.46″
- Sidewall
- 3.39″ / 86mm
- Circumference
- 77.82″
- Revs/Mile
- 814
Speedometer & Diameter Impact
Different rim — new wheels requiredAt an indicated 60 mph, your actual speed is 62.77 mph (101.02 km/h). Your speedometer reads 4.62% low versus actual speed.