Comparison
245/45 R19 vs 305/30 R20
Plus-sizing from 245/45 R19 to 305/30 R20 keeps overall diameter close to factory while opening room for a larger 20-inch wheel. This sizing approach shifts overall diameter slightly from OEM.
Expect a slight but noticeable shift in indicated speed compared to the original tires. The shorter sidewall gives the tire a firmer, more responsive feel and sharpens steering input. The wider section adds contact patch and lateral stability, while eating into fender and suspension clearance. The larger wheel shows more of the brake hardware and tightens up the wheel-gap look. Diameter change stays inside the conservative ±3% safety window — an OEM-safe fitment on most vehicles.
TakeA solid pick for drivers chasing a more aggressive stance without abandoning OEM rolling diameter.
Quick math: 305/30 R20 is 12.1 mm shorter than 245/45 R19, shifting the speedometer by -1.72%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
-12.1 mm
-1.72%
Speedometer at 100
98.3 km/h
-1.72% error
Ground clearance
-6.0 mm
ride height delta
Sidewall change
-18.8 mm
revs/km: 460.7
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/compare/245-45-r19-vs-305-30-r20Detailed comparison
| Metric | 245/45 R19 | 305/30 R20 | Difference |
|---|---|---|---|
| Overall diameter | 703.1 mm | 691.0 mm | -12.1 mm (-1.72%) |
| Sidewall height | 110.3 mm | 91.5 mm | -18.8 mm |
| Circumference | 2.209 m | 2.171 m | -38.0 mm |
| Revs / km | 452.7 | 460.7 | +7.9 |
| Ground clearance | reference | -6.0 mm | -6.0 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 98.3 km/h | -1.72 km/h |
Verdict: excellent
Within ±3% — speedometer, ABS and traction control should behave normally.
Speedometer impact
At a true 100 km/h, your dashboard will read 98.3 km/h after switching to 305/30 R20 — a -1.72% offset. Use the speedometer error calculator to recheck for other indicated speeds, and the speedometer error guide for the full background.
Ground clearance change
The new tire's half-diameter changes ride height by -6.0 mm. Small differences are absorbed by suspension travel, but anything beyond ±10 mm can affect headlight aim, fender clearance and bump-stop margin. See the plus-sizing guide before committing.
Back to
245/45 R19
Back to
305/30 R20
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