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305/35R18 in inches

A 305/35R18 tire is 26.4″ tall and 12.0″ wide, and fits a 18″ wheel. In inches it is written 26.4×12.0R18.

Diameter26.41″
Width12.01″
Sidewall4.20″
305/35R18 drawn to scale: 26.41 inch diameter, 4.20 inch sidewall, 18 inch wheel, 12.01 inch tread width18″ wheel4.20″26.41″ overall12.01″ wideSide view
Drawn to scale. Nominal dimensions calculated from the size code.
Manufacturer data

How tall 305/35R18 tires really are

Heights published by Toyo for all 3 tires in this size. Their published revolutions per mile work out to 25.7″ under load (below).

Real 305/35R18 tires measure 26.40–26.42″, against 26.41″ from the size code. They run both taller and shorter than the size code.

Height under load25.7″

Published revs per mile (786) mean the tire rolls like a 25.7″ tire on the vehicle. Use this for speedometer calibration.

Weight spread29.1–31.7 lb

The lightest (Toyo Proxes R, SL) is 2.6 lb lighter per corner than the heaviest (Toyo Proxes R888R, XL).

3 tires in 305/35R18

Sort by the spec you care about.

LoadRevs/miSource
Toyo Proxes RPerformanceSL · 101W26.4029.13.71,819786Spec page
Toyo Proxes RRPerformanceLL26.4230.23.61,433786Spec page
Toyo Proxes R888RPerformanceXL · 105Y26.4231.76.32,039786Spec page

Is 305/35R18 a 26-inch tire?

≈26″

Close. The size code works out to 26.41″, and the 3 tires here publish 26.40–26.42″, so people call it a 26.

Compare with nearby sizes

Differences in overall diameter, calculated from each size code.

SizeDiameter ″vs 305/35R18Difference
225/45R1825.97-0.43″-1.6%
255/40R1826.03-0.37″-1.4%
295/35R1826.13-0.28″-1.0%
235/45R1826.33-0.08″-0.3%
265/40R1826.35-0.06″-0.2%
215/50R1826.46+0.06″+0.2%
275/40R1826.66+0.26″+1.0%
245/45R1826.68+0.28″+1.0%
315/35R1826.68+0.28″+1.0%
225/50R1826.86+0.45″+1.7%

How to read 305/35R18

How to read any tire size

305/35R18 101W as printed on the tire sidewall, with each part numbered305/35R18 101W123456
How 305/35R18 101W is printed on the sidewall. It's the most common code among the 3 tires here (1 of them); 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

235Aspect ratio

A percentage, not a measurement: the sidewall is 35% as tall as the tire is wide, which is 106.8 mm or 4.20 inches.

3RConstruction

Radial construction.

418Wheel diameter

Mounts on a 18-inch wheel. Approved wheel widths run 10.0″ to 12.0″.

5101Load index

Each tire carries up to 1,819 lb (825 kg) at its maximum pressure.

6WSpeed rating

Rated for up to 168 mph sustained.

SpecificationInchesMetric
Overall diameter26.41671 mm
Section width12.01305 mm
Sidewall height4.20106.8 mm
Circumference83.02,107 mm
Revolutions per mile (calculated, unloaded)763.8475 per km
Revolutions per mile (published by manufacturers)786488 per km
Approved wheel width10.0–12.0254–305 mm

Speedometer error after switching to 305/35R18

Your actual speed– mph

Questions about 305/35R18

What is 305/35R18 in inches?

26.41 inches tall, 12.01 inches wide, on a 18-inch wheel. Written in inches, that is roughly 26.4×12.0R18.

How much does a 305/35R18 tire weigh?

Between 29.1 lb and 31.7 lb for the 3 tires listed here. The lightest is the Toyo Proxes R (SL); the heaviest is the Toyo Proxes R888R (XL).

What wheel width do I need for 305/35R18?

Manufacturers approve 10.0–12.0″ wide wheels for this size.

How many revolutions per mile does a 305/35R18 make?

Published figures run 786 revolutions per mile. The calculated figure is 763.8, but manufacturers measure the tire under load, where it rolls on a smaller radius.

How much taller is 305/35R18 than 265/40R18?

0.06 inches taller on paper (26.41″ vs 26.35″), which raises the axle about 0.03″. Your speedometer will read about 0.2% slow.