CarSpecsHQ

245/40R17 vs 205/55R16

205/55R16 is a safe swap for 245/40R17 by the usual ±3% rule: the diameter differs by +0.65%.

17" → 16"
245/40R17 24.72" · 205/55R16 24.88" · drawn to scale

Side by side

245/40R17205/55R16Difference
Overall diameter24.72"24.88"+0.16" (+0.65%)
Section width245 mm205 mm-40 mm
Sidewall3.86"4.44"+0.58"
Rim17"16"-1"
Circumference77.6"78.2"+0.5"
Revs per mile816811-5
Ride height——+0.08"
Speedometer reads 60 mph60.060.4+0.4 mph

Speedometer and odometer

020406080100120 reads 60 · actual 60.4 mph

With 205/55R16 on a car calibrated for 245/40R17, the speedometer reads 59.6 mph when you're really doing 60, and the odometer under-counts by 0.7%.

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

Other sizes close to 245/40R17

Questions

Can I replace 245/40R17 with 205/55R16?

205/55R16 is a safe swap for 245/40R17 by the usual ±3% rule: the diameter differs by +0.65%.

What's the difference between 245/40R17 and 205/55R16?

205/55R16 is 0.16" taller and 40 mm narrower; the sidewall is +0.58". At an indicated 60 mph you'd actually be doing 60.4 mph.

Will 205/55R16 fit on 245/40R17 wheels?

No — 245/40R17 needs a 17" wheel and 205/55R16 a 16" wheel. This is a plus/minus-size swap that changes wheels too.