tireheight.com

225/45R21 in inches

A 225/45R21 tire is 29.0″ tall and 8.9″ wide, and fits a 21″ wheel. In inches it is written 29.0×8.9R21.

Diameter28.97″
Width8.86″
Sidewall3.99″
225/45R21 drawn to scale: 28.97 inch diameter, 3.99 inch sidewall, 21 inch wheel, 8.86 inch tread width21″ wheel3.99″28.97″ overall8.86″ wideSide view
Drawn to scale. Nominal dimensions calculated from the size code.
Manufacturer data

How tall 225/45R21 tires really are

Heights published by Michelin for all 2 tires in this size. Their published revolutions per mile work out to 28.1″ under load (below).

Real 225/45R21 tires measure 28.90–28.94″, against 28.97″ from the size code. Every one runs shorter than the size code.

Height under load28.1″

Published revs per mile (719) mean the tire rolls like a 28.1″ tire on the vehicle. Use this for speedometer calibration.

Weight spread27.3–28.8 lb

The lightest (Michelin Primacy Tour A/S, SL) is 1.5 lb lighter per corner than the heaviest (Michelin X-Ice Snow, SL).

2 tires in 225/45R21

Sort by the spec you care about.

LoadRevs/miSource
Michelin Primacy Tour A/STouringSL · 95W28.9027.39.01,521719Spec page
Michelin X-Ice SnowWinterSL · 95H28.9428.810.51,521719Spec page

Is 225/45R21 a 29-inch tire?

≈29″

Yes. The size code works out to 28.97″, and the 2 tires here publish 28.90–28.94″, so people call it a 29.

All 29-inch tire sizes, on every wheel size.

Compare with nearby sizes

Differences in overall diameter, calculated from each size code.

SizeDiameter ″vs 225/45R21Difference
275/35R2128.58-0.39″-1.4%
325/30R2128.68-0.30″-1.0%
245/40R2128.72-0.26″-0.9%
285/35R2128.85-0.12″-0.4%
335/30R2128.91-0.06″-0.2%
255/40R2129.03+0.06″+0.2%
295/35R2129.13+0.16″+0.5%
345/30R2129.15+0.18″+0.6%
235/45R2129.33+0.35″+1.2%
265/40R2129.35+0.37″+1.3%

How to read 225/45R21

How to read any tire size

225/45R21 95W as printed on the tire sidewall, with each part numbered225/45R21 95W123456
How 225/45R21 95W is printed on the sidewall. It's the most common code among the 2 tires here (1 of them); tires in this size come in other load and speed ratings too.
1225Section width

225 mm across the widest point, or 8.86 inches. Every 225 size

245Aspect ratio

A percentage, not a measurement: the sidewall is 45% as tall as the tire is wide, which is 101.3 mm or 3.99 inches.

3RConstruction

Radial construction.

421Wheel diameter

Mounts on a 21-inch wheel. Approved wheel widths run 7.0″ to 8.5″.

595Load index

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

6WSpeed rating

Rated for up to 168 mph sustained.

SpecificationInchesMetric
Overall diameter28.97736 mm
Section width8.86225 mm
Sidewall height3.99101.3 mm
Circumference91.02,312 mm
Revolutions per mile (calculated, unloaded)696.1433 per km
Revolutions per mile (published by manufacturers)719447 per km
Approved wheel width7.0–8.5178–216 mm

Speedometer error after switching to 225/45R21

Your actual speed– mph

Questions about 225/45R21

What is 225/45R21 in inches?

28.97 inches tall, 8.86 inches wide, on a 21-inch wheel. Written in inches, that is roughly 29.0×8.9R21.

How much does a 225/45R21 tire weigh?

Between 27.3 lb and 28.8 lb for the 2 tires listed here. The lightest is the Michelin Primacy Tour A/S (SL); the heaviest is the Michelin X-Ice Snow (SL).

What wheel width do I need for 225/45R21?

Manufacturers approve 7.0–8.5″ wide wheels for this size.

How many revolutions per mile does a 225/45R21 make?

Published figures run 719 revolutions per mile. The calculated figure is 696.1, but manufacturers measure the tire under load, where it rolls on a smaller radius.

How much taller is 225/45R21 than 335/30R21?

0.06 inches taller on paper (28.97″ vs 28.91″), which raises the axle about 0.03″. Your speedometer will read about 0.2% slow.