CarSpecsHQ

235/35R20 vs 325/30R19

325/30R19 is a safe swap for 235/35R20 by the usual ±3% rule: the diameter differs by +0.76%.

20" → 19"
235/35R20 26.48" · 325/30R19 26.68" · drawn to scale

Side by side

235/35R20325/30R19Difference
Overall diameter26.48"26.68"+0.20" (+0.76%)
Section width235 mm325 mm+90 mm
Sidewall3.24"3.84"+0.60"
Rim20"19"-1"
Circumference83.2"83.8"+0.6"
Revs per mile762756-6
Ride height——+0.10"
Speedometer reads 60 mph60.060.5+0.5 mph

Speedometer and odometer

020406080100120 reads 60 · actual 60.5 mph

With 325/30R19 on a car calibrated for 235/35R20, the speedometer reads 59.5 mph when you're really doing 60, and the odometer under-counts by 0.8%.

Speedo showsActual speed
30 mph30.2 mph
45 mph45.3 mph
60 mph60.5 mph
70 mph70.5 mph
80 mph80.6 mph

Other sizes close to 235/35R20

Questions

Can I replace 235/35R20 with 325/30R19?

325/30R19 is a safe swap for 235/35R20 by the usual ±3% rule: the diameter differs by +0.76%.

What's the difference between 235/35R20 and 325/30R19?

325/30R19 is 0.20" taller and 90 mm wider; the sidewall is +0.60". At an indicated 60 mph you'd actually be doing 60.5 mph.

Will 325/30R19 fit on 235/35R20 wheels?

No — 235/35R20 needs a 20" wheel and 325/30R19 a 19" wheel. This is a plus/minus-size swap that changes wheels too.