225/45R18 vs 245/40R19Tire Size Comparison

Safe

The 2.9% diameter difference is within the accepted 3% tolerance.

225/45R18660mm dia245/40R19679mm dia+9.4mm

Comparison Details

Overall Diameter659.7 vs 678.6 mm (+18.9 mm)
Diameter Difference+2.86%
Section Width225 vs 245 mm (+20 mm)
Sidewall Height101.3 vs 98.0 mm (-3.3 mm)
Circumference2072.5 vs 2131.9 mm
Clearance Change+9.4 mm
Speedometer Error+2.86%
Revs/Mile777 vs 755

Speedometer Correction

When switching from 225/45R18 to 245/40R19, your speedometer will differ from actual speed.

SpeedometerActual SpeedDifference
30 km/h30.9 km/h+0.9 km/h
40 km/h41.1 km/h+1.1 km/h
50 km/h51.4 km/h+1.4 km/h
60 km/h61.7 km/h+1.7 km/h
70 km/h72.0 km/h+2.0 km/h
80 km/h82.3 km/h+2.3 km/h
90 km/h92.6 km/h+2.6 km/h
100 km/h102.9 km/h+2.9 km/h
110 km/h113.2 km/h+3.2 km/h
120 km/h123.4 km/h+3.4 km/h
130 km/h133.7 km/h+3.7 km/h

Vehicles Using These Sizes

Vehicles with 225/45R18

2025 BMW 3 Series330i2025 BMW 3 Series330i xDrive2024 BMW 3 Series330i2024 BMW 3 Series330i xDrive2023 BMW 3 Series330i2023 BMW 3 Series330i xDrive2022 BMW 3 Series330i2022 BMW 3 Series330i xDrive2021 BMW 3 Series330i2021 BMW 3 Series330i xDrive2020 BMW 3 Series330i2020 BMW 3 Series330i xDrive2025 Cadillac CT5Luxury2024 Cadillac CT5Luxury2023 Cadillac CT5Luxury2022 Cadillac CT5Luxury2025 Genesis G702.0T2024 Genesis G702.0T2023 Genesis G702.0T2022 Genesis G702.0T2021 Genesis G702.0T2020 Genesis G702.0T2025 Mercedes-Benz C-ClassC 3002025 Mercedes-Benz C-ClassC 300 4MATIC2024 Mercedes-Benz C-ClassC 3002024 Mercedes-Benz C-ClassC 300 4MATIC2023 Mercedes-Benz C-ClassC 3002023 Mercedes-Benz C-ClassC 300 4MATIC2022 Mercedes-Benz C-ClassC 3002022 Mercedes-Benz C-ClassC 300 4MATIC2021 Mercedes-Benz C-ClassC 3002021 Mercedes-Benz C-ClassC 300 4MATIC2020 Mercedes-Benz C-ClassC 3002020 Mercedes-Benz C-ClassC 300 4MATIC2025 Volkswagen JettaGLI2024 Volkswagen JettaGLI2023 Volkswagen JettaGLI2022 Volkswagen JettaGLI2021 Volkswagen JettaGLI2020 Volkswagen JettaGLI

Vehicles with 245/40R19

2021 Genesis G803.3T2020 Genesis G803.3T2025 Infiniti Q50Red Sport 4002024 Infiniti Q50Red Sport 4002023 Infiniti Q50Red Sport 4002022 Infiniti Q50Red Sport 4002021 Infiniti Q50Red Sport 4002020 Infiniti Q50Red Sport 4002025 Volvo S60Ultimate B6 AWD2023 Volvo S60B6 R-Design2022 Volvo S60T6 R-Design2021 Volvo S60T6 R-Design2020 Volvo S60T6 R-Design

Individual Tire Size Details

225/45R18
Full specifications, compatible vehicles, and alternatives
245/40R19
Full specifications, compatible vehicles, and alternatives

Practical Guidance

Switching from 225/45R18 to 245/40R19 is within the industry-accepted 3% diameter tolerance. Your speedometer, ABS, and traction control should function normally. Note: these sizes require different rim diameters (18" vs 19"), so you will need different wheels.

The 3% diameter tolerance is a widely accepted industry guideline referenced by the ETRTO and most vehicle manufacturers. When in doubt, consult your vehicle's owner's manual or a qualified tire professional. For U.S. tire safety standards and recalls, see the NHTSA Tire Safety page.

Frequently Asked Questions

Safe. The overall diameter differs by 2.86%, width changes by 20mm.

Speedometer error will be 2.86%. At an indicated 100 km/h, actual speed is about 102.9 km/h.

Ground clearance changes by +9.4mm per side.