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235/45R21 vs 265/45R20 tire size comparison

235/45R21265/45R20

265/45R20 is 0.1 in (0.21%) taller than 235/45R21 and 1.1 in wider. They fit different wheels: 235/45R21 a 21-inch wheel and 265/45R20 a 20-inch wheel.

235/45R21 and 265/45R20 side by side

+0.1 in / +0.21%235/45R21: 29.3 in tall, solid line265/45R20: 29.4 in tall, dashed line235/45R21Width 9.3 in (235 mm)Sidewall 4.2 in (106 mm)265/45R20Width 10.4 in (265 mm)Sidewall 4.7 in (119 mm)
235/45R21 is drawn with a solid line and 265/45R20 with a dashed line. In each drawing both tires are to the same scale; the tread shoulder and bead curves are simplified. The table below has the same numbers.
Dimensions of 235/45R21 and 265/45R20, with the difference (265/45R20 minus 235/45R21)
Measurement235/45R21265/45R20DifferenceDifference %
Section width9.3 in (235 mm)10.4 in (265 mm)+1.1 in (+30 mm)+12.77%
Sidewall height4.2 in (106 mm)4.7 in (119 mm)+0.5 in (+13 mm)+12.77%
Wheel (rim) diameter21.0 in (533 mm)20.0 in (508 mm)-1.0 in (-25 mm)-4.76%
Overall diameter29.3 in (745 mm)29.4 in (747 mm)+0.1 in (+2 mm)+0.21%
Circumference92.1 in (2340 mm)92.3 in (2345 mm)+0.2 in (+5 mm)+0.21%
Revolutions per mile688686-2-0.21%

Differences are 265/45R20 minus 235/45R21; percentages are relative to 235/45R21. These are nominal design dimensions. Real tires vary by brand, tread depth, wheel width, load and pressure.

The overall diameter differs by 0.21%, which is within the common 3% rule of thumb.

The rule of thumb keeps a replacement size within about 3% of the original overall diameter. It covers diameter only. It is not a fit, load or safety check, because width, wheel diameter, load capacity and clearance matter too. Confirm any size change with your vehicle's owner's manual or a tire professional.

Speedometer difference

When the speedometer reads 60 mph on a vehicle built for 235/45R21, the actual speed on 265/45R20 is about 60.1 mph. When it reads 60 mph on a vehicle built for 265/45R20, the actual speed on 235/45R21 is about 59.9 mph. These figures assume the speedometer is accurate on the original size and use nominal dimensions, so treat them as estimates.

Actual speed for a given speedometer reading, 235/45R21 against 265/45R20
Speedometer readsActual on 265/45R20 (built for 235/45R21)Actual on 235/45R21 (built for 265/45R20)
20 mph20.0 mph20.0 mph
30 mph30.1 mph29.9 mph
40 mph40.1 mph39.9 mph
50 mph50.1 mph49.9 mph
60 mph60.1 mph59.9 mph
70 mph70.2 mph69.8 mph
80 mph80.2 mph79.8 mph

A common rule of thumb is to keep a replacement size within about 3% of the original overall diameter. Check the tire placard on the driver's door jamb and your owner's manual for the sizes your vehicle was built for. Confirm any size change with your vehicle's owner's manual or a tire professional.

Which vehicles use each size?

These vehicles list the size among their verified sizes, by trim. Open one to see all of its sizes.

Check it in the calculator

The calculator takes the same two sizes and shows the full comparison, or lets you swap either one for another size.

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Shop for 235/45R21 or 265/45R20 tires

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Other comparisons with 235/45R21

Side-by-side dimensions and speedometer difference for sizes close to 235/45R21 in overall diameter.

Other comparisons with 265/45R20

Side-by-side dimensions and speedometer difference for sizes close to 265/45R20 in overall diameter.

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