245/45R18 in inches

A 245/45R18 tire is 26.7″ tall and 9.6″ wide, and fits a 18″ wheel. In inches it is written 26.7×9.6R18.

Diameter26.68″

Width9.65″

Sidewall4.34″

Drawn to scale. Nominal dimensions calculated from the size code.

Manufacturer data

How tall 245/45R18 tires really are

Heights published by BFGoodrich, General, Michelin and Toyo for all 25 tires in this size. Their published revolutions per mile work out to 25.9″ under load (below).

Real 245/45R18 tires measure 26.60–26.70″, against 26.68″ from the size code. They run both taller and shorter than the size code.

Height under load25.9″

Published revs per mile (779–780) mean the tire rolls like a 25.9″ tire on the vehicle. Use this for speedometer calibration.

Weight spread23.0–31.9 lb

The lightest (General AltiMAX RT45, XL) is 8.9 lb lighter per corner than the heaviest (Michelin Primacy Tour A/S, SL).

25 tires in 245/45R18

Sort by the spec you care about.

	Load					Revs/mi	Source
General AltiMAX RT45Touring	XL · 100V	26.70	23.0	11.0	1,764	779	Spec page
General AltiMAX365 AWTouring	XL · 100V	26.70	23.0	11.0	1,764	779	Spec page
General G-MAX RSPerformance	XL · 100Y	26.70	23.3	10.0	1,764	779	Spec page
Michelin Primacy Tour A/STouring	XL · 100H	26.70	23.8	9.0	1,764	780	Spec page
Toyo Proxes Sport 2Performance	XL · 100Y	26.70	24.1	9.2	1,764	779	Spec page
Toyo Extensa HP IIPerformance	XL · 100W	26.65	24.3	9.6	1,764	779	Spec page
Michelin Primacy All SeasonTouring	SL · 96V	26.70	25.0	8.5	1,565	780	Spec page
Michelin Pilot Alpin PA4Winter	XL · 100V	26.65	25.1	10.5	1,764	780	Spec page
General G-MAX AS07Performance	XL · 100W	26.70	25.5	10.0	1,764	779	Spec page
Michelin Pilot Sport 4 SPerformance	XL · 100(Y)	26.70	25.6	9.5	1,764	780	Spec page
Michelin CrossClimate2All-season	XL · 100V	26.60	25.8	10.0	1,764	780	Spec page
Michelin X-Ice SnowWinter	XL · 100H	26.65	26.3	10.5	1,764	780	Spec page
BFGoodrich g-Force Phenom T/APerformance	XL · 100Y	26.65	26.4	8.0	1,764	780	Spec page
Michelin Pilot Sport All-Season 4Performance	XL · 100Y	26.70	26.5	10.0	1,764	780	Spec page
Toyo Celsius IITouring	XL · 100V	26.65	26.5	11.3	1,764	779	Spec page
Toyo Proxes Sport A/SPerformance	XL · 100Y	26.65	26.7	9.6	1,764	779	Spec page
BFGoodrich Advantage ControlAll-season	XL · 100V	26.65	26.8	10.5	1,764	780	Spec page
Michelin Primacy Tour A/STouring	SL · 96V	26.70	27.3	9.0	1,565	780	Spec page
Toyo Proxes G-Tour	XL · 100V	26.70	27.6	11.7	1,764	779	Spec page
Toyo Observe G3-IceWinter	XL · 100T	26.65	28.7	11.3	1,764	779	Spec page
BFGoodrich g-Force COMP-2 A/S PLUSPerformance	XL · 100Y	26.65	28.7	9.0	1,565	780	Spec page
Michelin Pilot Sport 4Performance	XL · 100Y	26.70	28.9	9.5	1,764	780	Spec page
Michelin Primacy Tour A/STouring	SL · 96V	26.70	30.5	9.0	1,565	780	Spec page
Michelin Primacy 3Performance	XL · 100Y	26.65	30.7	9.0	1,764	780	Spec page
Michelin Primacy Tour A/STouring	SL · 96V	26.70	31.9	8.5	1,565	780	Spec page

Is 245/45R18 a 27-inch tire?

≈27″

Yes. The size code works out to 26.68″, and the 25 tires here publish 26.60–26.70″, so people call it a 27.

All 27-inch tire sizes, on every wheel size.

Compare with nearby sizes

Differences in overall diameter, calculated from each size code.

Size	Diameter ″	vs 245/45R18	Difference
295/35R18	26.13	-0.55″	-2.1%
235/45R18	26.33	-0.35″	-1.3%
265/40R18	26.35	-0.33″	-1.3%
305/35R18	26.41	-0.28″	-1.0%
215/50R18	26.46	-0.22″	-0.8%
275/40R18	26.66	-0.02″	-0.1%
315/35R18	26.68	0.00″	0.0%
225/50R18	26.86	+0.18″	+0.7%
285/40R18	26.98	+0.30″	+1.1%
255/45R18	27.04	+0.35″	+1.3%

How to read 245/45R18

How to read any tire size

How 245/45R18 100Y is printed on the sidewall. It's the most common code among the 25 tires here (8 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.

418Wheel diameter

Mounts on a 18-inch wheel. Approved wheel widths run 7.5″ to 9.0″.

5100Load index

Each tire carries up to 1,764 lb (800 kg) at its maximum pressure.

6YSpeed rating

Rated for up to 186 mph sustained.

XLExtra load

Printed after the size. In this size the XL tires carry up to 1,764 lb each and the standard-load tires up to 1,565 lb, as published.

Specification	Inches	Metric
Overall diameter	26.68	678 mm
Section width	9.65	245 mm
Sidewall height	4.34	110.2 mm
Circumference	83.8	2,129 mm
Revolutions per mile (calculated, unloaded)	755.9	470 per km
Revolutions per mile (published by manufacturers)	779–780	484–485 per km
Approved wheel width	7.5–9.0	191–229 mm

Speedometer error after switching to 245/45R18

Your actual speed– mph

Questions about 245/45R18

What is 245/45R18 in inches?

26.68 inches tall, 9.65 inches wide, on a 18-inch wheel. Written in inches, that is roughly 26.7×9.6R18.

How much does a 245/45R18 tire weigh?

Between 23.0 lb and 31.9 lb for the 25 tires listed here. The lightest is the General AltiMAX RT45 (XL); the heaviest is the Michelin Primacy Tour A/S (SL).

What wheel width do I need for 245/45R18?

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

How many revolutions per mile does a 245/45R18 make?

Published figures run 779–780 revolutions per mile. The calculated figure is 755.9, but manufacturers measure the tire under load, where it rolls on a smaller radius.

How much taller is 245/45R18 than 275/40R18?

0.02 inches taller on paper (26.68″ vs 26.66″), which raises the axle about 0.01″. Your speedometer will read about 0.1% slow.