Comparison
245/35 R20 vs 305/30 R20
Stepping from 245/35 R20 to 305/30 R20 keeps the 20-inch wheel but widens the section by 60 mm. This tire combination moves rolling diameter a touch off the original spec. Expect a slight but noticeable shift in indicated speed compared to the original tires. Less sidewall flex usually translates to crisper turn-in and a slightly stiffer ride over rough pavement. Diameter change stays inside the conservative ±3% safety window — an OEM-safe fitment on most vehicles.
TakeReasonable performance-leaning swap as long as fender and suspension clearance check out.
Quick math: 305/30 R20 is 11.5 mm taller than 245/35 R20, shifting the speedometer by +1.69%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
+11.5 mm
1.69%
Speedometer at 100
101.7 km/h
+1.69% error
Ground clearance
+5.8 mm
ride height delta
Sidewall change
+5.8 mm
revs/km: 460.7
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/compare/245-35-r20-vs-305-30-r20Detailed comparison
| Metric | 245/35 R20 | 305/30 R20 | Difference |
|---|---|---|---|
| Overall diameter | 679.5 mm | 691.0 mm | +11.5 mm (+1.69%) |
| Sidewall height | 85.8 mm | 91.5 mm | +5.8 mm |
| Circumference | 2.135 m | 2.171 m | +36.1 mm |
| Revs / km | 468.4 | 460.7 | -7.8 |
| Ground clearance | reference | +5.8 mm | +5.8 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 101.7 km/h | +1.69 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 101.7 km/h after switching to 305/30 R20 — a +1.69% 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 +5.8 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
245/35 R20
Back to
305/30 R20
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