Tire size
275/35 R21
Full dimensions and a live comparison calculator for the 275/35 R21 tire size.
Overall diameter
725.9 mm
28.58″
Sidewall height
96.3 mm
Circumference
2.280 m
Revs / km
438.5
Section width
275 mm
Aspect ratio
35%
Rim diameter
21″
533.4 mm
Radius
362.9 mm
What does 275/35 R21 mean?
The 275 is the section width in millimetres, measured sidewall to sidewall. The 35 is the aspect ratio — sidewall height as a percentage of width, so the sidewall here is 96.3 mm. The R21 means a radial-construction tire designed for a 21-inch wheel rim. Together these give an overall diameter of 726 mm.
Compare 275/35 R21 with another size
Current Tire
New Tire
Ground line · scaled comparison
Not Recommended
Over 5% — speedometer & ABS may misread
Diameter change
-91.6 mm
-12.62%
Speedometer at 100
87.4 km/h
-12.62% error
Ground clearance
-45.8 mm
ride height delta
Sidewall change
+5.0 mm
revs/km: 501.8
Permalink for this comparison:
/compare/275-35-r21-vs-225-45-r17Common alternatives to 275/35 R21
These sizes are within a few percent overall diameter — usually safe on the same vehicle from a speedometer-error standpoint.
Compare 275/35 R21 with popular upgrades
Plus-size upgrades from 275/35 R21
Fitment safety note
Overall diameter, speedometer error and circumference are only part of the picture. Physical clearance, wheel offset (ET), hub bore, suspension geometry, load index and your manufacturer's recommendation all decide whether a size is truly safe on your car. Always cross-check with the vehicle manual or a qualified fitter before changing tire size.