Question 1

Which tire is taller, 255/35 R18 or 255/35 R19?

Accepted Answer

255/35 R19 is taller by 25.4 mm (4.00%) compared with 255/35 R18.

Question 2

What is the diameter difference between 255/35 R18 and 255/35 R19?

Accepted Answer

255/35 R18 measures 636 mm overall diameter, 255/35 R19 measures 661 mm — a difference of 25.4 mm (4.00%).

Question 3

How much speedometer error does this change create?

Accepted Answer

Switching from 255/35 R18 to 255/35 R19 changes the speedometer reading by +4.00%. At an indicated 100 km/h, your true speed becomes about 104.0 km/h.

Question 4

Is 255/35 R19 a safe replacement for 255/35 R18?

Accepted Answer

Between 3% and 5% diameter difference — speedometer drift is noticeable. Consider recalibration and confirm clearance with your vehicle's manufacturer specification.

Question 5

What else should I check before changing tire size?

Accepted Answer

Beyond diameter and speedometer error, verify wheel offset (ET), rim width, hub bore, load index, brake and suspension clearance, and your vehicle's manufacturer specification. Local regulations may also limit how far you can deviate from OEM.

Metric	255/35 R18	255/35 R19	Difference
Overall diameter	635.7 mm	661.1 mm	+25.4 mm (+4.00%)
Sidewall height	89.3 mm	89.3 mm	0.0 mm
Circumference	1.997 m	2.077 m	+79.8 mm
Revs / km	500.7	481.5	-19.2
Ground clearance	reference	+12.7 mm	+12.7 mm
Speedometer @ 100 km/h	100.0 km/h	104.0 km/h	+4.00 km/h

255/35 R18 vs 255/35 R19

Detailed comparison

Verdict: warning

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