Question 1

Which tire is taller, 155/70 R13 or 155/80 R13?

Accepted Answer

155/80 R13 is taller by 31.0 mm (5.67%) compared with 155/70 R13.

Question 2

What is the diameter difference between 155/70 R13 and 155/80 R13?

Accepted Answer

155/70 R13 measures 547 mm overall diameter, 155/80 R13 measures 578 mm — a difference of 31.0 mm (5.67%).

Question 3

How much speedometer error does this change create?

Accepted Answer

Switching from 155/70 R13 to 155/80 R13 changes the speedometer reading by +5.67%. At an indicated 100 km/h, your true speed becomes about 105.7 km/h.

Question 4

Is 155/80 R13 a safe replacement for 155/70 R13?

Accepted Answer

Over 5% diameter difference. This is outside the common safe range and can affect speedometer accuracy, ABS calibration and gearing. Not recommended without professional review.

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	155/70 R13	155/80 R13	Difference
Overall diameter	547.2 mm	578.2 mm	+31.0 mm (+5.67%)
Sidewall height	108.5 mm	124.0 mm	+15.5 mm
Circumference	1.719 m	1.816 m	+97.4 mm
Revs / km	581.7	550.5	-31.2
Ground clearance	reference	+15.5 mm	+15.5 mm
Speedometer @ 100 km/h	100.0 km/h	105.7 km/h	+5.67 km/h

155/70 R13 vs 155/80 R13

Detailed comparison

Verdict: danger

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