Question 1

Which tire is taller, 175/65 R15 or 225/45 R17?

Accepted Answer

225/45 R17 is taller by 25.8 mm (4.24%) compared with 175/65 R15.

Question 2

What is the diameter difference between 175/65 R15 and 225/45 R17?

Accepted Answer

175/65 R15 measures 609 mm overall diameter, 225/45 R17 measures 634 mm — a difference of 25.8 mm (4.24%).

Question 3

How much speedometer error does this change create?

Accepted Answer

Switching from 175/65 R15 to 225/45 R17 changes the speedometer reading by +4.24%. At an indicated 100 km/h, your true speed becomes about 104.2 km/h.

Question 4

Is 225/45 R17 a safe replacement for 175/65 R15?

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	175/65 R15	225/45 R17	Difference
Overall diameter	608.5 mm	634.3 mm	+25.8 mm (+4.24%)
Sidewall height	113.8 mm	101.3 mm	-12.5 mm
Circumference	1.912 m	1.993 m	+81.1 mm
Revs / km	523.1	501.8	-21.3
Ground clearance	reference	+12.9 mm	+12.9 mm
Speedometer @ 100 km/h	100.0 km/h	104.2 km/h	+4.24 km/h

175/65 R15 vs 225/45 R17

Detailed comparison

Verdict: warning

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