Question 1

Which tire is taller, 185/55 R16 or 245/35 R18?

Accepted Answer

245/35 R18 is taller by 18.8 mm (3.08%) compared with 185/55 R16.

Question 2

What is the diameter difference between 185/55 R16 and 245/35 R18?

Accepted Answer

185/55 R16 measures 610 mm overall diameter, 245/35 R18 measures 629 mm — a difference of 18.8 mm (3.08%).

Question 3

How much speedometer error does this change create?

Accepted Answer

Switching from 185/55 R16 to 245/35 R18 changes the speedometer reading by +3.08%. At an indicated 100 km/h, your true speed becomes about 103.1 km/h.

Question 4

Is 245/35 R18 a safe replacement for 185/55 R16?

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	185/55 R16	245/35 R18	Difference
Overall diameter	609.9 mm	628.7 mm	+18.8 mm (+3.08%)
Sidewall height	101.8 mm	85.8 mm	-16.0 mm
Circumference	1.916 m	1.975 m	+59.1 mm
Revs / km	521.9	506.3	-15.6
Ground clearance	reference	+9.4 mm	+9.4 mm
Speedometer @ 100 km/h	100.0 km/h	103.1 km/h	+3.08 km/h

185/55 R16 vs 245/35 R18

Detailed comparison

Verdict: warning

Related comparisons

Frequently asked questions