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285/40R23 in inches

A 285/40R23 tire is 32.0″ tall and 11.2″ wide, and fits a 23″ wheel. In inches it is written 32.0×11.2R23.

Diameter31.98″
Width11.22″
Sidewall4.49″
285/40R23 drawn to scale: 31.98 inch diameter, 4.49 inch sidewall, 23 inch wheel, 11.22 inch tread width23″ wheel4.49″31.98″ overall11.22″ wideSide view
Drawn to scale. Nominal dimensions calculated from the size code.
Manufacturer data

How tall 285/40R23 tires really are

Heights published by Michelin for all 3 tires in this size. Their published revolutions per mile work out to 31.0″ under load (below).

Real 285/40R23 tires measure 32.00″, against 31.98″ from the size code. Every one runs taller than the size code.

Height under load31.0″

Published revs per mile (651) mean the tire rolls like a 31.0″ tire on the vehicle. Use this for speedometer calibration.

Weight spread34.7–42.8 lb

The lightest (Michelin Pilot Sport 4 S, XL) is 8.1 lb lighter per corner than the heaviest (Michelin Primacy All Season, XL).

3 tires in 285/40R23

Sort by the spec you care about.

LoadRevs/miSource
Michelin Pilot Sport 4 SPerformanceXL · 111(Y)32.0034.79.52,403651Spec page
Michelin Pilot Sport All-Season 4PerformanceXL · 111Y32.0036.09.52,403651Spec page
Michelin Primacy All SeasonTouringXL · 111Y32.0042.88.52,403651Spec page

Is 285/40R23 a 32-inch tire?

≈32″

Yes. The size code works out to 31.98″, and the 3 tires here publish 32.00″, so people call it a 32.

All 32-inch tire sizes, on every wheel size.

Compare with nearby sizes

Differences in overall diameter, calculated from each size code.

SizeDiameter ″vs 285/40R23Difference
335/30R2330.91-1.06″-3.3%
295/35R2331.13-0.85″-2.6%
305/40R2231.61-0.37″-1.2%
275/45R2231.74-0.23″-0.7%
285/35R2431.85-0.12″-0.4%
325/35R2331.96-0.02″-0.1%
285/45R2232.10+0.12″+0.4%
295/35R2432.13+0.15″+0.5%
325/40R2232.24+0.26″+0.8%
305/40R2332.61+0.63″+2.0%

How to read 285/40R23

How to read any tire size

285/40R23 111Y as printed on the tire sidewall, with each part numbered285/40R23 111Y123456
How 285/40R23 111Y is printed on the sidewall. It's the most common code among the 3 tires here (2 of them); tires in this size come in other load and speed ratings too.
1285Section width

285 mm across the widest point, or 11.22 inches. Every 285 size

240Aspect ratio

A percentage, not a measurement: the sidewall is 40% as tall as the tire is wide, which is 114.0 mm or 4.49 inches.

3RConstruction

Radial construction.

423Wheel diameter

Mounts on a 23-inch wheel. Approved wheel widths run 9.5″ to 11.0″.

5111Load index

Each tire carries up to 2,403 lb (1,090 kg) at its maximum pressure.

6YSpeed rating

Rated for up to 186 mph sustained.

XLExtra load

Printed after the size.

SpecificationInchesMetric
Overall diameter31.98812 mm
Section width11.22285 mm
Sidewall height4.49114.0 mm
Circumference100.52,552 mm
Revolutions per mile (calculated, unloaded)630.7392 per km
Revolutions per mile (published by manufacturers)651405 per km
Approved wheel width9.5–11.0241–279 mm

Speedometer error after switching to 285/40R23

Your actual speed– mph

Questions about 285/40R23

What is 285/40R23 in inches?

31.98 inches tall, 11.22 inches wide, on a 23-inch wheel. Written in inches, that is roughly 32.0×11.2R23.

How much does a 285/40R23 tire weigh?

Between 34.7 lb and 42.8 lb for the 3 tires listed here. The lightest is the Michelin Pilot Sport 4 S (XL); the heaviest is the Michelin Primacy All Season (XL).

What wheel width do I need for 285/40R23?

Manufacturers approve 9.5–11.0″ wide wheels for this size.

How many revolutions per mile does a 285/40R23 make?

Published figures run 651 revolutions per mile. The calculated figure is 630.7, but manufacturers measure the tire under load, where it rolls on a smaller radius.

How much taller is 285/40R23 than 325/35R23?

0.02 inches taller on paper (31.98″ vs 31.96″), which raises the axle about 0.01″. Your speedometer will read about 0.1% slow.