tireheight.com

235/30R20 in inches

A 235/30R20 tire is 25.6″ tall and 9.3″ wide, and fits a 20″ wheel. In inches it is written 25.6×9.3R20.

Diameter25.55″
Width9.25″
Sidewall2.78″
235/30R20 drawn to scale: 25.55 inch diameter, 2.78 inch sidewall, 20 inch wheel, 9.25 inch tread width20″ wheel2.78″25.55″ overall9.25″ wideSide view
Drawn to scale. Nominal dimensions calculated from the size code.
Manufacturer data

How tall 235/30R20 tires really are

Heights published by Michelin for the one tire in this size. Their published revolutions per mile work out to 24.8″ under load (below).

The one tire listed, the Michelin Pilot Sport 4 S, measures 25.60″: 0.05″ taller than the size code's 25.55″.

Height under load24.8″

Published revs per mile (813) mean the tire rolls like a 24.8″ tire on the vehicle. Use this for speedometer calibration.

1 tire in 235/30R20

Sort by the spec you care about.

LoadRevs/miSource
Michelin Pilot Sport 4 SPerformanceXL · 88(Y)25.6021.29.51,235813Spec page

Is 235/30R20 a 26-inch tire?

≈26″

Close. The size code works out to 25.55″, and the 1 tire here publishes 25.60″, so people call it a 26.

Compare with nearby sizes

Differences in overall diameter, calculated from each size code.

SizeDiameter ″vs 235/30R20Difference
225/30R2025.31-0.24″-0.9%
235/35R1925.48-0.07″-0.3%
275/30R1925.50-0.06″-0.2%
285/25R2025.61+0.06″+0.2%
245/30R2025.79+0.24″+0.9%
295/25R2025.81+0.26″+1.0%
305/25R2026.00+0.45″+1.8%
255/30R2026.02+0.47″+1.8%
225/35R2026.20+0.65″+2.5%
265/30R2026.26+0.71″+2.8%

How to read 235/30R20

How to read any tire size

235/30R20 88Y as printed on the tire sidewall, with each part numbered235/30R20 88Y123456
How 235/30R20 88Y 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.
1235Section width

235 mm across the widest point, or 9.25 inches. Every 235 size

230Aspect ratio

A percentage, not a measurement: the sidewall is 30% as tall as the tire is wide, which is 70.5 mm or 2.78 inches.

3RConstruction

Radial construction.

420Wheel diameter

Mounts on a 20-inch wheel. Approved wheel widths run 8.5″ to 8.5″.

588Load index

Each tire carries up to 1,235 lb (560 kg) at its maximum pressure.

6YSpeed rating

Rated for up to 186 mph sustained.

XLExtra load

Printed after the size.

SpecificationInchesMetric
Overall diameter25.55649 mm
Section width9.25235 mm
Sidewall height2.7870.5 mm
Circumference80.32,039 mm
Revolutions per mile (calculated, unloaded)789.3490 per km
Revolutions per mile (published by manufacturers)813505 per km
Approved wheel width8.5216 mm

Speedometer error after switching to 235/30R20

Your actual speed– mph

Questions about 235/30R20

What is 235/30R20 in inches?

25.55 inches tall, 9.25 inches wide, on a 20-inch wheel. Written in inches, that is roughly 25.6×9.3R20.

What wheel width do I need for 235/30R20?

Manufacturers approve 8.5″ wide wheels for this size.

How many revolutions per mile does a 235/30R20 make?

Published figures run 813 revolutions per mile. The calculated figure is 789.3, but manufacturers measure the tire under load, where it rolls on a smaller radius.

How much taller is 235/30R20 than 225/30R20?

0.24 inches taller on paper (25.55″ vs 25.31″), which raises the axle about 0.12″. Your speedometer will read about 0.9% slow.