235/40R19vs315/30R19
Proportional side-by-side visual comparison, dimensional specs, speedometer calibration, and fitment guide.
Comparison Summary & Verdict
Comparing 235/40R19 (baseline) to 315/30R19 (target):The 315/30R19 is 0.04" taller in overall diameter (+0.15%) and 3.15" wider.
Side-by-Side Dimension Specifications
Full dimensional metrics calculated according to ISO standardized tire formulas.
| Specification | 235/40R19 (Stock) | 315/30R19 (Target) | Difference (Delta) |
|---|---|---|---|
| Overall Diameter | 26.4" (671 mm) | 26.44" (672 mm) | +0.04" (+0.15%) |
| Section Width | 9.25" (235 mm) | 12.4" (315 mm) | +3.15" (+80 mm) |
| Sidewall Height | 3.7" (94 mm) | 3.72" (94 mm) | +0.02" |
| Circumference | 82.94" (2107 mm) | 83.07" (2110 mm) | +0.13" |
| Revolutions per Mile | 788 revs/mi | 786 revs/mi | -2 revs/mi |
| Wheel Rim Diameter | 19" | 19" | Same wheel diameter (Direct fit) |
| Recommended Rim Width | 6.3" – 8.2" | 8.5" – 11.0" | n/a |
Speedometer & Odometer Calibration Table
Because vehicle speedometers measure axle rotation, changing tire circumference alters speed readings. When switching from 235/40R19 to 315/30R19:
| Actual Speed (GPS) | Speedometer Reading on 315/30R19 | Variance / Error |
|---|---|---|
| 20 mph | 20.0 mph | -0.0 mph |
| 30 mph | 30.0 mph | -0.0 mph |
| 45 mph | 44.9 mph | -0.1 mph |
| 60 mph | 59.9 mph | -0.1 mph |
| 70 mph | 69.9 mph | -0.1 mph |
| 80 mph | 79.9 mph | -0.1 mph |
Fitment & Practical Considerations
Clearance & Rubbing
Because 315/30R19 is significantly different in size (+0.04" taller), check clearance with suspension components, brake calipers, and wheel wells at full steering lock and full compression.
Gearing & Acceleration
Gearing and acceleration changes will be negligible between these two sizes.
Wheel & Rim Width
Both sizes use a standard 19" wheel rim. Ensure your existing rim width falls within 8.5" to 11.0" for optimal tire bead seating.
Official Calculation Standards & References
All dimension formulas, revs/mile conversions, rim width brackets, and speedometer error deltas on Tire Visualizer are calculated strictly according to international automotive engineering standards:
ISO 4000-1 metric tire dimensional standards, section width ratios, and approved measuring rim definitions.
North American standards for overall tire diameter, static loaded radius, and revolutions-per-mile benchmarks.
Federal motor vehicle safety standards governing pneumatic tire sizing, load indices, and speedometer tolerance limits.
Engineering standards (SAE J2047 & J1982) for dynamic tire rolling radius and speedometer calibration accuracy.
Frequently Asked Questions: 235/40R19 vs 315/30R19
Can I replace 235/40R19 with 315/30R19?
Yes. The diameter difference between 235/40R19 and 315/30R19 is 0.15%, which is within the industry standard ±3% safety margin. It is generally a safe direct replacement without requiring speedometer recalibration or suspension modifications.
How does 315/30R19 affect my speedometer compared to 235/40R19?
When driving at an actual speed of 60 mph on 315/30R19, your speedometer will read 59.9 mph (a difference of 0.1 mph). Your vehicle will be traveling slightly faster than indicated.
Will 315/30R19 change my vehicle's ride height?
315/30R19 has an overall diameter of 26.44" compared to 26.4" on 235/40R19. This will change your ground clearance by +0.02 inches (lift).
What wheel rim width is needed for 315/30R19?
For 315/30R19, the recommended wheel rim width range is typically 8.5" to 11.0" wide, mounted on a 19" diameter wheel.
Compare Other Tire Sizes
Select any two tire sizes to generate an instant visual diagram.