315/70R17 vs 305/65R19
305/65R19 is taller than 315/70R17 by 0.72% — a diameter difference of 0.25″.
What changes between 315/70R17 and 305/65R19
Switching from 315/70R17 to 305/65R19 changes overall diameter by +0.72%, a taller tire by 0.25 inches. This lands inside the ±3% fitment safe zone, so most vehicles will accept the swap without rubbing, speedometer recalibration, or ABS/TPMS complications. Section width moves by -0.39″ (315mm → 305mm), which affects contact patch and fender-well clearance. Sidewall height shifts by -0.87″: a shorter sidewall sharpens steering response at the cost of ride comfort and rim protection. Revs per mile moves by -4, which translates directly to speedometer error — at an indicated 65 mph, actual speed becomes 65.5 mph. The swap also changes rim diameter from 17″ to 19″, meaning new wheels are required. Wheel cost typically dominates the total upsize budget.
| Spec | 315/70R17 | 305/65R19 |
|---|---|---|
| Overall diameter | 34.36″ | 34.61″ |
| Section width | 12.4″ (315 mm) | 12.01″ (305 mm) |
| Sidewall height | 8.68″ (70%) | 7.81″ (65%) |
| Rim diameter | 17″ | 19″ |
| Circumference | 107.95″ | 108.73″ |
| Revs per mile | 587 | 583 |
Interactive comparison
275/65R18 or "33" for inch aliases315/70R17
- Diameter
- 34.36″ / 872.8mm
- Section Width
- 12.4″
- Sidewall
- 8.68″ / 220.5mm
- Circumference
- 107.95″
- Revs/Mile
- 587
305/65R19
- Diameter
- 34.61″ / 879.1mm
- Section Width
- 12.01″
- Sidewall
- 7.81″ / 198.25mm
- Circumference
- 108.73″
- Revs/Mile
- 583
Speedometer & Diameter Impact
Different rim — new wheels requiredAt an indicated 60 mph, your actual speed is 60.43 mph (97.26 km/h). Your speedometer reads 0.72% low versus actual speed.