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315/30R23 in inches

A 315/30R23 tire is 30.4″ tall and 12.4″ wide, and fits a 23″ wheel. In inches it is written 30.4×12.4R23.

Diameter30.44″
Width12.40″
Sidewall3.72″
315/30R23 drawn to scale: 30.44 inch diameter, 3.72 inch sidewall, 23 inch wheel, 12.40 inch tread width23″ wheel3.72″30.44″ overall12.40″ wideSide view
Drawn to scale. Nominal dimensions calculated from the size code.
Manufacturer data

How tall 315/30R23 tires really are

Heights published by Michelin for all 2 tires in this size. Their published revolutions per mile work out to 29.5″ under load (below).

Real 315/30R23 tires measure 30.47–30.50″, against 30.44″ from the size code. Every one runs taller than the size code.

Height under load29.5″

Published revs per mile (683) mean the tire rolls like a 29.5″ tire on the vehicle. Use this for speedometer calibration.

Weight spread33.5–38.4 lb

The lightest (Michelin Pilot Sport 4 S, XL) is 4.9 lb lighter per corner than the heaviest (Michelin Pilot Alpin 5, XL).

2 tires in 315/30R23

Sort by the spec you care about.

LoadRevs/miSource
Michelin Pilot Sport 4 SPerformanceXL · 108(Y)30.5033.59.02,205683Spec page
Michelin Pilot Alpin 5WinterXL · 108W30.4738.410.52,205683Spec page

Is 315/30R23 a 30-inch tire?

≈30″

Close. The size code works out to 30.44″, and the 2 tires here publish 30.47–30.50″, 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 315/30R23Difference
255/40R2230.03-0.41″-1.3%
295/35R2230.13-0.31″-1.0%
265/40R2230.35-0.09″-0.3%
305/35R2230.41-0.04″-0.1%
275/40R2230.66+0.22″+0.7%
315/35R2230.68+0.24″+0.8%
285/35R2330.85+0.41″+1.4%
335/30R2330.91+0.47″+1.6%
325/35R2230.96+0.52″+1.7%
295/35R2331.13+0.69″+2.3%

How to read 315/30R23

How to read any tire size

315/30R23 108W as printed on the tire sidewall, with each part numbered315/30R23 108W123456
How 315/30R23 108W 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.
1315Section width

315 mm across the widest point, or 12.40 inches. Every 315 size

230Aspect ratio

A percentage, not a measurement: the sidewall is 30% as tall as the tire is wide, which is 94.5 mm or 3.72 inches.

3RConstruction

Radial construction.

423Wheel diameter

Mounts on a 23-inch wheel. Approved wheel widths run 10.5″ to 11.5″.

5108Load index

Each tire carries up to 2,205 lb (1,000 kg) at its maximum pressure.

6WSpeed rating

Rated for up to 168 mph sustained.

XLExtra load

Printed after the size.

SpecificationInchesMetric
Overall diameter30.44773 mm
Section width12.40315 mm
Sidewall height3.7294.5 mm
Circumference95.62,429 mm
Revolutions per mile (calculated, unloaded)662.5412 per km
Revolutions per mile (published by manufacturers)683424 per km
Approved wheel width10.5–11.5267–292 mm

Speedometer error after switching to 315/30R23

Your actual speed– mph

Questions about 315/30R23

What is 315/30R23 in inches?

30.44 inches tall, 12.40 inches wide, on a 23-inch wheel. Written in inches, that is roughly 30.4×12.4R23.

How much does a 315/30R23 tire weigh?

Between 33.5 lb and 38.4 lb for the 2 tires listed here. The lightest is the Michelin Pilot Sport 4 S (XL); the heaviest is the Michelin Pilot Alpin 5 (XL).

What wheel width do I need for 315/30R23?

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

How many revolutions per mile does a 315/30R23 make?

Published figures run 683 revolutions per mile. The calculated figure is 662.5, but manufacturers measure the tire under load, where it rolls on a smaller radius.