CarSpecsHQ

345/30R19 vs 215/55R18

215/55R18 is a safe swap for 345/30R19 by the usual ±3% rule: the diameter differs by +0.59%.

19" → 18"
345/30R19 27.15" · 215/55R18 27.31" · drawn to scale

Side by side

345/30R19215/55R18Difference
Overall diameter27.15"27.31"+0.16" (+0.59%)
Section width345 mm215 mm-130 mm
Sidewall4.07"4.66"+0.58"
Rim19"18"-1"
Circumference85.3"85.8"+0.5"
Revs per mile743738-4
Ride height——+0.08"
Speedometer reads 60 mph60.060.4+0.4 mph

Speedometer and odometer

020406080100120 reads 60 · actual 60.4 mph

With 215/55R18 on a car calibrated for 345/30R19, the speedometer reads 59.6 mph when you're really doing 60, and the odometer under-counts by 0.6%.

Speedo showsActual speed
30 mph30.2 mph
45 mph45.3 mph
60 mph60.4 mph
70 mph70.4 mph
80 mph80.5 mph

Other sizes close to 345/30R19

Questions

Can I replace 345/30R19 with 215/55R18?

215/55R18 is a safe swap for 345/30R19 by the usual ±3% rule: the diameter differs by +0.59%.

What's the difference between 345/30R19 and 215/55R18?

215/55R18 is 0.16" taller and 130 mm narrower; the sidewall is +0.58". At an indicated 60 mph you'd actually be doing 60.4 mph.

Will 215/55R18 fit on 345/30R19 wheels?

No — 345/30R19 needs a 19" wheel and 215/55R18 a 18" wheel. This is a plus/minus-size swap that changes wheels too.