Question 1

Which tire is taller, 175/55 R16 or 245/40 R17?

Accepted Answer

245/40 R17 is taller by 28.9 mm (4.83%) compared with 175/55 R16.

Question 2

What is the diameter difference between 175/55 R16 and 245/40 R17?

Accepted Answer

175/55 R16 measures 599 mm overall diameter, 245/40 R17 measures 628 mm — a difference of 28.9 mm (4.83%).

Question 3

How much speedometer error does this change create?

Accepted Answer

Switching from 175/55 R16 to 245/40 R17 changes the speedometer reading by +4.83%. At an indicated 100 km/h, your true speed becomes about 104.8 km/h.

Question 4

Is 245/40 R17 a safe replacement for 175/55 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	175/55 R16	245/40 R17	Difference
Overall diameter	598.9 mm	627.8 mm	+28.9 mm (+4.83%)
Sidewall height	96.3 mm	98.0 mm	+1.8 mm
Circumference	1.881 m	1.972 m	+90.8 mm
Revs / km	531.5	507.0	-24.5
Ground clearance	reference	+14.4 mm	+14.4 mm
Speedometer @ 100 km/h	100.0 km/h	104.8 km/h	+4.83 km/h

175/55 R16 vs 245/40 R17

Detailed comparison

Verdict: warning

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