Question 1

Which tire is taller, 245/40 R20 or 295/30 R22?

Accepted Answer

295/30 R22 is taller by 31.8 mm (4.52%) compared with 245/40 R20.

Question 2

What is the diameter difference between 245/40 R20 and 295/30 R22?

Accepted Answer

245/40 R20 measures 704 mm overall diameter, 295/30 R22 measures 736 mm — a difference of 31.8 mm (4.52%).

Question 3

How much speedometer error does this change create?

Accepted Answer

Switching from 245/40 R20 to 295/30 R22 changes the speedometer reading by +4.52%. At an indicated 100 km/h, your true speed becomes about 104.5 km/h.

Question 4

Is 295/30 R22 a safe replacement for 245/40 R20?

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	245/40 R20	295/30 R22	Difference
Overall diameter	704.0 mm	735.8 mm	+31.8 mm (+4.52%)
Sidewall height	98.0 mm	88.5 mm	-9.5 mm
Circumference	2.212 m	2.312 m	+99.9 mm
Revs / km	452.1	432.6	-19.5
Ground clearance	reference	+15.9 mm	+15.9 mm
Speedometer @ 100 km/h	100.0 km/h	104.5 km/h	+4.52 km/h

245/40 R20 vs 295/30 R22

Detailed comparison

Verdict: warning

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