tireheight.com

305/25R20 in inches

A 305/25R20 tire is 26.0″ tall and 12.0″ wide, and fits a 20″ wheel. In inches it is written 26.0×12.0R20.

Diameter26.00″
Width12.01″
Sidewall3.00″
305/25R20 drawn to scale: 26.00 inch diameter, 3.00 inch sidewall, 20 inch wheel, 12.01 inch tread width20″ wheel3.00″26.00″ overall12.01″ wideSide view
Drawn to scale. Nominal dimensions calculated from the size code.
Manufacturer data

How tall 305/25R20 tires really are

Heights published by Michelin for the one tire in this size. Their published revolutions per mile work out to 25.2″ under load (below).

The one tire listed, the Michelin Pilot Sport 4 S, measures 26.00″: 0.00″ shorter than the size code's 26.00″.

Height under load25.2″

Published revs per mile (801) mean the tire rolls like a 25.2″ tire on the vehicle. Use this for speedometer calibration.

1 tire in 305/25R20

Sort by the spec you care about.

LoadRevs/miSource
Michelin Pilot Sport 4 SPerformanceXL · 97(Y)26.0027.49.51,609801Spec page

Is 305/25R20 a 26-inch tire?

≈26″

Yes. The size code works out to 26.00″, and the 1 tire here publishes 26.00″, so people call it a 26.

Compare with nearby sizes

Differences in overall diameter, calculated from each size code.

SizeDiameter ″vs 305/25R20Difference
235/30R2025.55-0.45″-1.7%
285/25R2025.61-0.39″-1.5%
245/30R2025.79-0.22″-0.8%
295/25R2025.81-0.20″-0.8%
255/30R2026.02+0.02″+0.1%
225/35R2026.20+0.20″+0.8%
265/30R2026.26+0.26″+1.0%
325/25R2026.40+0.39″+1.5%
235/35R2026.48+0.47″+1.8%
275/30R2026.50+0.49″+1.9%

How to read 305/25R20

How to read any tire size

305/25R20 97Y as printed on the tire sidewall, with each part numbered305/25R20 97Y123456
How 305/25R20 97Y 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.
1305Section width

305 mm across the widest point, or 12.01 inches. Every 305 size

225Aspect ratio

A percentage, not a measurement: the sidewall is 25% as tall as the tire is wide, which is 76.3 mm or 3.00 inches.

3RConstruction

Radial construction.

420Wheel diameter

Mounts on a 20-inch wheel. Approved wheel widths run 10.5″ to 11.5″.

597Load index

Each tire carries up to 1,609 lb (730 kg) at its maximum pressure.

6YSpeed rating

Rated for up to 186 mph sustained.

XLExtra load

Printed after the size.

SpecificationInchesMetric
Overall diameter26.00660 mm
Section width12.01305 mm
Sidewall height3.0076.3 mm
Circumference81.72,075 mm
Revolutions per mile (calculated, unloaded)775.6482 per km
Revolutions per mile (published by manufacturers)801498 per km
Approved wheel width10.5–11.5267–292 mm

Speedometer error after switching to 305/25R20

Your actual speed– mph

Questions about 305/25R20

What is 305/25R20 in inches?

26.00 inches tall, 12.01 inches wide, on a 20-inch wheel. Written in inches, that is roughly 26.0×12.0R20.

What wheel width do I need for 305/25R20?

Manufacturers approve 10.5–11.5″ wide wheels for this size.

How many revolutions per mile does a 305/25R20 make?

Published figures run 801 revolutions per mile. The calculated figure is 775.6, but manufacturers measure the tire under load, where it rolls on a smaller radius.

How much taller is 305/25R20 than 295/25R20?

0.20 inches taller on paper (26.00″ vs 25.81″), which raises the axle about 0.10″. Your speedometer will read about 0.8% slow.