Comparison

225/35 R19 vs 265/40 R18

265/40 R18 drops the rim from 19 to 18 inches versus 225/35 R19, trading wheel size for taller sidewall. This sizing approach swings rolling diameter far enough to feel on the road.

The speedometer error is noticeable and may warrant a recalibration if you rely on indicated speed. The taller sidewall adds cushioning over potholes and rougher roads, with a softer overall ride. Extra width broadens the footprint for more grip, but check inner liner and strut clearance before fitting. Minus-sizing keeps replacement costs down and opens up a wider range of winter and all-terrain tires. Diameter delta falls in the cautious 3–5% range, where speedometer recalibration and a careful clearance check are worth doing.

TakePractical direction for winter wheels, chains, or rougher pavement where cushioning matters.

Quick math: 265/40 R18 is 29.1 mm taller than 225/35 R19, shifting the speedometer by +4.55%.

Current Tire

225/35R19

New Tire

265/40R18
225/35 R19
265/40 R18

Ground line · scaled comparison

Slight Difference

Within ±5% — usable, recalibration recommended

Diameter change

+29.1 mm

4.55%

Speedometer at 100

104.5 km/h

+4.55% error

Ground clearance

+14.6 mm

ride height delta

Sidewall change

+27.3 mm

revs/km: 475.7

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Detailed comparison

Metric225/35 R19265/40 R18Difference
Overall diameter640.1 mm669.2 mm+29.1 mm (+4.55%)
Sidewall height78.8 mm106.0 mm+27.3 mm
Circumference2.011 m2.102 m+91.4 mm
Revs / km497.3475.7-21.6
Ground clearancereference+14.6 mm+14.6 mm
Speedometer @ 100 km/h100.0 km/h104.5 km/h+4.55 km/h

Verdict: warning

Between 3% and 5% — noticeable speedometer drift; recalibration may be advisable.

Speedometer impact

At a true 100 km/h, your dashboard will read 104.5 km/h after switching to 265/40 R18 — a +4.55% 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 +14.6 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

225/35 R19

Back to

265/40 R18

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Frequently asked questions