235/45R19 vs 275/35R20

Q: Can I replace 235/45R19 with 275/35R20?

275/35R20 is a safe swap for 235/45R19 by the usual ±3% rule: the diameter differs by +0.92%.

275/35R20 is a safe swap for 235/45R19 by the usual ±3% rule: the diameter differs by +0.92%.

235/45R19 27.33" · 275/35R20 27.58" · drawn to scale

Side by side

	235/45R19	275/35R20	Difference
Overall diameter	27.33"	27.58"	+0.25" (+0.92%)
Section width	235 mm	275 mm	+40 mm
Sidewall	4.16"	3.79"	-0.37"
Rim	19"	20"	+1"
Circumference	85.8"	86.6"	+0.8"
Revs per mile	738	731	-7
Ride height	—	—	+0.13"
Speedometer reads 60 mph	60.0	60.6	+0.6 mph

Speedometer and odometer

With 275/35R20 on a car calibrated for 235/45R19, the speedometer reads 59.5 mph when you're really doing 60, and the odometer under-counts by 0.9%.

Speedo shows	Actual speed
30 mph	30.3 mph
45 mph	45.4 mph
60 mph	60.6 mph
70 mph	70.6 mph
80 mph	80.7 mph

Other sizes close to 235/45R19

Questions

Can I replace 235/45R19 with 275/35R20?

275/35R20 is a safe swap for 235/45R19 by the usual ±3% rule: the diameter differs by +0.92%.

What's the difference between 235/45R19 and 275/35R20?

275/35R20 is 0.25" taller and 40 mm wider; the sidewall is -0.37". At an indicated 60 mph you'd actually be doing 60.6 mph.

Will 275/35R20 fit on 235/45R19 wheels?

No — 235/45R19 needs a 19" wheel and 275/35R20 a 20" wheel. This is a plus/minus-size swap that changes wheels too.