Comparison
245/40 R20 vs 305/30 R20
305/30 R20 is a lower-profile take on 245/40 R20 — same 20-inch wheel, shorter sidewall. This wheel and tire pairing 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. More tread on the ground tends to improve dry grip and stance, with a small fuel-economy and clearance tradeoff. Diameter change stays inside the conservative ±3% safety window — an OEM-safe fitment on most vehicles.
TakeSuits drivers who value sharper steering and appearance over outright ride softness.
Quick math: 305/30 R20 is 13.0 mm shorter than 245/40 R20, shifting the speedometer by -1.85%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
-13.0 mm
-1.85%
Speedometer at 100
98.2 km/h
-1.85% error
Ground clearance
-6.5 mm
ride height delta
Sidewall change
-6.5 mm
revs/km: 460.7
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/compare/245-40-r20-vs-305-30-r20Detailed comparison
| Metric | 245/40 R20 | 305/30 R20 | Difference |
|---|---|---|---|
| Overall diameter | 704.0 mm | 691.0 mm | -13.0 mm (-1.85%) |
| Sidewall height | 98.0 mm | 91.5 mm | -6.5 mm |
| Circumference | 2.212 m | 2.171 m | -40.8 mm |
| Revs / km | 452.1 | 460.7 | +8.5 |
| Ground clearance | reference | -6.5 mm | -6.5 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 98.2 km/h | -1.85 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 98.2 km/h after switching to 305/30 R20 — a -1.85% 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 -6.5 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
245/40 R20
Back to
305/30 R20
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