CarSpecsHQ

215/50R17 vs 275/35R18

275/35R18 is a safe swap for 215/50R17 by the usual ±3% rule: the diameter differs by +0.45%.

17" → 18"
215/50R17 25.46" · 275/35R18 25.58" · drawn to scale

Side by side

215/50R17275/35R18Difference
Overall diameter25.46"25.58"+0.11" (+0.45%)
Section width215 mm275 mm+60 mm
Sidewall4.23"3.79"-0.44"
Rim17"18"+1"
Circumference80.0"80.4"+0.4"
Revs per mile792788-4
Ride height——+0.06"
Speedometer reads 60 mph60.060.3+0.3 mph

Speedometer and odometer

020406080100120 reads 60 · actual 60.3 mph

With 275/35R18 on a car calibrated for 215/50R17, the speedometer reads 59.7 mph when you're really doing 60, and the odometer under-counts by 0.4%.

Speedo showsActual speed
30 mph30.1 mph
45 mph45.2 mph
60 mph60.3 mph
70 mph70.3 mph
80 mph80.4 mph

Other sizes close to 215/50R17

Questions

Can I replace 215/50R17 with 275/35R18?

275/35R18 is a safe swap for 215/50R17 by the usual ±3% rule: the diameter differs by +0.45%.

What's the difference between 215/50R17 and 275/35R18?

275/35R18 is 0.11" taller and 60 mm wider; the sidewall is -0.44". At an indicated 60 mph you'd actually be doing 60.3 mph.

Will 275/35R18 fit on 215/50R17 wheels?

No — 215/50R17 needs a 17" wheel and 275/35R18 a 18" wheel. This is a plus/minus-size swap that changes wheels too.