Question 1

Which tire is taller, 275/40 R22 or 275/45 R20?

Accepted Answer

275/40 R22 is taller by 23.3 mm (2.99%) compared with 275/45 R20.

Question 2

What is the diameter difference between 275/40 R22 and 275/45 R20?

Accepted Answer

275/40 R22 measures 779 mm overall diameter, 275/45 R20 measures 756 mm — a difference of 23.3 mm (2.99%).

Question 3

How much speedometer error does this change create?

Accepted Answer

Switching from 275/40 R22 to 275/45 R20 changes the speedometer reading by -2.99%. At an indicated 100 km/h, your true speed becomes about 97.0 km/h.

Question 4

Is 275/45 R20 a safe replacement for 275/40 R22?

Accepted Answer

Within ±3% diameter — generally considered a safe replacement from a speedometer-error standpoint, provided wheel offset, rim width and clearance also match your vehicle.

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	275/40 R22	275/45 R20	Difference
Overall diameter	778.8 mm	755.5 mm	-23.3 mm (-2.99%)
Sidewall height	110.0 mm	123.8 mm	+13.8 mm
Circumference	2.447 m	2.373 m	-73.2 mm
Revs / km	408.7	421.3	+12.6
Ground clearance	reference	-11.6 mm	-11.6 mm
Speedometer @ 100 km/h	100.0 km/h	97.0 km/h	-2.99 km/h

275/40 R22 vs 275/45 R20

Detailed comparison

Verdict: excellent

Related comparisons

Frequently asked questions