tireheight.com

245/45R21 in inches

A 245/45R21 tire is 29.7″ tall and 9.6″ wide, and fits a 21″ wheel. In inches it is written 29.7×9.6R21.

Diameter29.68″
Width9.65″
Sidewall4.34″
245/45R21 drawn to scale: 29.68 inch diameter, 4.34 inch sidewall, 21 inch wheel, 9.65 inch tread width21″ wheel4.34″29.68″ overall9.65″ wideSide view
Drawn to scale. Nominal dimensions calculated from the size code.
Manufacturer data

How tall 245/45R21 tires really are

Heights published by Michelin for all 4 tires in this size. Their published revolutions per mile work out to 28.7″ under load (below).

Real 245/45R21 tires measure 29.60–29.70″, against 29.68″ from the size code. They run both taller and shorter than the size code.

Height under load28.7″

Published revs per mile (702) mean the tire rolls like a 28.7″ tire on the vehicle. Use this for speedometer calibration.

Weight spread29.7–32.2 lb

The lightest (Michelin CrossClimate2, XL) is 2.5 lb lighter per corner than the heaviest (Michelin X-Ice Snow, XL).

4 tires in 245/45R21

Sort by the spec you care about.

LoadRevs/miSource
Michelin CrossClimate2All-seasonXL · 104V29.6029.710.01,984702Spec page
Michelin Pilot Sport All-Season 4PerformanceXL · 104Y29.7029.910.01,984702Spec page
Michelin Pilot Sport 4 SUVPerformanceXL · 104W29.7031.29.51,984702Spec page
Michelin X-Ice SnowWinterXL · 104H29.6532.210.51,984702Spec page

Is 245/45R21 a 30-inch tire?

≈30″

Yes. The size code works out to 29.68″, and the 4 tires here publish 29.60–29.70″, so people call it a 30.

All 30-inch tire sizes, on every wheel size.

Compare with nearby sizes

Differences in overall diameter, calculated from each size code.

SizeDiameter ″vs 245/45R21Difference
295/35R2129.13-0.55″-1.9%
345/30R2129.15-0.53″-1.8%
235/45R2129.33-0.35″-1.2%
265/40R2129.35-0.33″-1.1%
305/35R2129.41-0.28″-0.9%
275/40R2129.66-0.02″-0.1%
315/35R2129.680.00″0.0%
285/40R2129.98+0.30″+1.0%
255/45R2130.04+0.35″+1.2%
235/50R2130.25+0.57″+1.9%

How to read 245/45R21

How to read any tire size

245/45R21 104V as printed on the tire sidewall, with each part numbered245/45R21 104V123456
How 245/45R21 104V is printed on the sidewall. It's the most common code among the 4 tires here (1 of them); tires in this size come in other load and speed ratings too.
1245Section width

245 mm across the widest point, or 9.65 inches. Every 245 size

245Aspect ratio

A percentage, not a measurement: the sidewall is 45% as tall as the tire is wide, which is 110.2 mm or 4.34 inches.

3RConstruction

Radial construction.

421Wheel diameter

Mounts on a 21-inch wheel. Approved wheel widths run 7.5″ to 9.0″.

5104Load index

Each tire carries up to 1,984 lb (900 kg) at its maximum pressure.

6VSpeed rating

Rated for up to 149 mph sustained.

XLExtra load

Printed after the size.

SpecificationInchesMetric
Overall diameter29.68754 mm
Section width9.65245 mm
Sidewall height4.34110.2 mm
Circumference93.22,368 mm
Revolutions per mile (calculated, unloaded)679.5422 per km
Revolutions per mile (published by manufacturers)702436 per km
Approved wheel width7.5–9.0191–229 mm

Speedometer error after switching to 245/45R21

Your actual speed– mph

Questions about 245/45R21

What is 245/45R21 in inches?

29.68 inches tall, 9.65 inches wide, on a 21-inch wheel. Written in inches, that is roughly 29.7×9.6R21.

How much does a 245/45R21 tire weigh?

Between 29.7 lb and 32.2 lb for the 4 tires listed here. The lightest is the Michelin CrossClimate2 (XL); the heaviest is the Michelin X-Ice Snow (XL).

What wheel width do I need for 245/45R21?

Manufacturers approve 7.5–9.0″ wide wheels for this size.

How many revolutions per mile does a 245/45R21 make?

Published figures run 702 revolutions per mile. The calculated figure is 679.5, but manufacturers measure the tire under load, where it rolls on a smaller radius.

How much taller is 245/45R21 than 275/40R21?

0.02 inches taller on paper (29.68″ vs 29.66″), which raises the axle about 0.01″. Your speedometer will read about 0.1% slow.