CarSpecsHQ

235/35R20 vs 275/30R20

275/30R20 is a safe swap for 235/35R20 by the usual ±3% rule: the diameter differs by +0.07%.

20" rim
235/35R20 26.48" · 275/30R20 26.50" · drawn to scale

Side by side

235/35R20275/30R20Difference
Overall diameter26.48"26.50"+0.02" (+0.07%)
Section width235 mm275 mm+40 mm
Sidewall3.24"3.25"+0.01"
Rim20"20"same
Circumference83.2"83.2"+0.1"
Revs per mile762761-1
Ride height——+0.01"
Speedometer reads 60 mph60.060.0+0.0 mph

Speedometer and odometer

020406080100120 reads 60 · actual 60.0 mph

With 275/30R20 on a car calibrated for 235/35R20, the speedometer reads 60.0 mph when you're really doing 60, and the odometer under-counts by 0.1%.

Speedo showsActual speed
30 mph30.0 mph
45 mph45.0 mph
60 mph60.0 mph
70 mph70.1 mph
80 mph80.1 mph

Other sizes close to 235/35R20

Questions

Can I replace 235/35R20 with 275/30R20?

275/30R20 is a safe swap for 235/35R20 by the usual ±3% rule: the diameter differs by +0.07%.

What's the difference between 235/35R20 and 275/30R20?

275/30R20 is 0.02" taller and 40 mm wider; the sidewall is +0.01". At an indicated 60 mph you'd actually be doing 60.0 mph.

Will 275/30R20 fit on 235/35R20 wheels?

Both use a 20" rim, so the wheel diameter matches; check the wheel's width range for a 275 mm tire and the fender clearance.