Comparison
235/45 R18 vs 245/35 R20
Switching from 235/45 R18 to 245/35 R20 is a plus-2 upgrade that wraps a shorter sidewall around a larger 20-inch wheel. This setup trims or stretches rolling diameter by a small margin.
The speedometer offset is small but measurable; worth keeping in mind if you watch the dash closely. Less sidewall flex usually translates to crisper turn-in and a slightly stiffer ride over rough pavement. More tread on the ground tends to improve dry grip and stance, with a small fuel-economy and clearance tradeoff. Visually, the bigger wheel fills the arch and gives the car a more aggressive stance. Diameter change stays inside the conservative ±3% safety window — an OEM-safe fitment on most vehicles.
TakeCommon upgrade for sportier handling and a tighter wheel-gap look on the same vehicle.
Quick math: 245/35 R20 is 10.8 mm taller than 235/45 R18, shifting the speedometer by +1.62%.
Current Tire
New Tire
Ground line · scaled comparison
Excellent Fit
Within ±3% — safe for daily driving
Diameter change
+10.8 mm
1.62%
Speedometer at 100
101.6 km/h
+1.62% error
Ground clearance
+5.4 mm
ride height delta
Sidewall change
-20.0 mm
revs/km: 468.4
Permalink for this comparison:
/compare/235-45-r18-vs-245-35-r20Detailed comparison
| Metric | 235/45 R18 | 245/35 R20 | Difference |
|---|---|---|---|
| Overall diameter | 668.7 mm | 679.5 mm | +10.8 mm (+1.62%) |
| Sidewall height | 105.8 mm | 85.8 mm | -20.0 mm |
| Circumference | 2.101 m | 2.135 m | +33.9 mm |
| Revs / km | 476.0 | 468.4 | -7.6 |
| Ground clearance | reference | +5.4 mm | +5.4 mm |
| Speedometer @ 100 km/h | 100.0 km/h | 101.6 km/h | +1.62 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 101.6 km/h after switching to 245/35 R20 — a +1.62% 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 +5.4 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
235/45 R18
Back to
245/35 R20
Drivers also compare
Closely-related fitments and plus-size swaps for 235/45 R18 and 245/35 R20.
245/35 R20 vs 285/30 R20
Wider variation on the same rim — more grip, less clearance.
Δ 0.07%
235/45 R18 vs 265/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 0.07%
245/35 R20 vs 255/35 R20
Wider variation on the same rim — more grip, less clearance.
Δ 1.03%
235/45 R18 vs 255/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.12%
235/45 R18 vs 275/40 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.27%
235/45 R18 vs 245/45 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.35%
225/45 R18 vs 235/45 R18
Wider variation on the same rim — more grip, less clearance.
Δ 1.36%
245/35 R20 vs 305/30 R20
Wider variation on the same rim — more grip, less clearance.
Δ 1.69%
Related topics