215/45R20 in inches

A 215/45R20 tire is 27.6″ tall and 8.5″ wide, and fits a 20″ wheel. In inches it is written 27.6×8.5R20.

Diameter27.62″

Width8.46″

Sidewall3.81″

Drawn to scale. Nominal dimensions calculated from the size code.

Manufacturer data

How tall 215/45R20 tires really are

Heights published by Michelin for the one tire in this size. Their published revolutions per mile work out to 26.8″ under load (below).

The one tire listed, the Michelin Pilot Sport 4 S, measures 27.60″: 0.02″ shorter than the size code's 27.62″.

Height under load26.8″

Published revs per mile (753) mean the tire rolls like a 26.8″ tire on the vehicle. Use this for speedometer calibration.

1 tire in 215/45R20

Sort by the spec you care about.

	Load					Revs/mi	Source
Michelin Pilot Sport 4 SPerformance	XL · 95(Y)	27.60	24.4	9.5	1,521	753	Spec page

Is 215/45R20 a 28-inch tire?

≈28″

Close. The size code works out to 27.62″, and the 1 tire here publishes 27.60″, so people call it a 28.

All 28-inch tire sizes, on every wheel size.

Compare with nearby sizes

Differences in overall diameter, calculated from each size code.

Size	Diameter ″	vs 215/45R20	Difference
305/30R20	27.20	-0.41″	-1.5%
265/35R20	27.30	-0.31″	-1.1%
235/40R20	27.40	-0.22″	-0.8%
315/30R20	27.44	-0.18″	-0.6%
275/35R20	27.58	-0.04″	-0.1%
325/30R20	27.68	+0.06″	+0.2%
245/40R20	27.72	+0.10″	+0.4%
285/35R20	27.85	+0.24″	+0.9%
335/30R20	27.91	+0.30″	+1.1%
255/40R20	28.03	+0.41″	+1.5%

How to read 215/45R20

How to read any tire size

How 215/45R20 95Y is printed on the sidewall. It's the most common code among the 1 tire here; tires in this size come in other load and speed ratings too.

1215Section width

215 mm across the widest point, or 8.46 inches. Every 215 size

245Aspect ratio

A percentage, not a measurement: the sidewall is 45% as tall as the tire is wide, which is 96.8 mm or 3.81 inches.

3RConstruction

Radial construction.

420Wheel diameter

Mounts on a 20-inch wheel. Approved wheel widths run 7.0″ to 8.0″.

595Load index

Each tire carries up to 1,521 lb (690 kg) at its maximum pressure.

6YSpeed rating

Rated for up to 186 mph sustained.

XLExtra load

Printed after the size.

Specification	Inches	Metric
Overall diameter	27.62	702 mm
Section width	8.46	215 mm
Sidewall height	3.81	96.8 mm
Circumference	86.8	2,204 mm
Revolutions per mile (calculated, unloaded)	730.2	454 per km
Revolutions per mile (published by manufacturers)	753	468 per km
Approved wheel width	7.0–8.0	178–203 mm

Speedometer error after switching to 215/45R20

Your actual speed– mph

Questions about 215/45R20

What is 215/45R20 in inches?

27.62 inches tall, 8.46 inches wide, on a 20-inch wheel. Written in inches, that is roughly 27.6×8.5R20.

What wheel width do I need for 215/45R20?

Manufacturers approve 7.0–8.0″ wide wheels for this size.

How many revolutions per mile does a 215/45R20 make?

Published figures run 753 revolutions per mile. The calculated figure is 730.2, but manufacturers measure the tire under load, where it rolls on a smaller radius.

How much taller is 215/45R20 than 275/35R20?

0.04 inches taller on paper (27.62″ vs 27.58″), which raises the axle about 0.02″. Your speedometer will read about 0.1% slow.