CarSpecsHQ

265/70R18 vs 305/65R17

305/65R17 is a safe swap for 265/70R18 by the usual ±3% rule: the diameter differs by +0.01%.

18" → 17"
265/70R18 32.61" · 305/65R17 32.61" · drawn to scale

Side by side

265/70R18305/65R17Difference
Overall diameter32.61"32.61"+0.00" (+0.01%)
Section width265 mm305 mm+40 mm
Sidewall7.30"7.81"+0.50"
Rim18"17"-1"
Circumference102.4"102.4"+0.0"
Revs per mile619618-0
Ride height——+0.00"
Speedometer reads 60 mph60.060.0+0.0 mph

Speedometer and odometer

020406080100120 reads 60 · actual 60.0 mph

With 305/65R17 on a car calibrated for 265/70R18, the speedometer reads 60.0 mph when you're really doing 60, and the odometer under-counts by 0.0%.

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

Other sizes close to 265/70R18

Questions

Can I replace 265/70R18 with 305/65R17?

305/65R17 is a safe swap for 265/70R18 by the usual ±3% rule: the diameter differs by +0.01%.

What's the difference between 265/70R18 and 305/65R17?

305/65R17 is 0.00" taller and 40 mm wider; the sidewall is +0.50". At an indicated 60 mph you'd actually be doing 60.0 mph.

Will 305/65R17 fit on 265/70R18 wheels?

No — 265/70R18 needs a 18" wheel and 305/65R17 a 17" wheel. This is a plus/minus-size swap that changes wheels too.