245/45R17 Tire Size in Inches

Diameter, width, sidewall and the closest equivalent sizes, computed from the size code.

245/45R17
25.7" tall × 9.6" wide
On a 17-inch wheel · roughly 25.7x9.6R17 in flotation sizing
MeasurementInchesMillimetres
Overall diameter25.68652
Section width9.65245
Sidewall height4.34110.2
Wheel diameter17432
Circumference80.72049
Revolutions per mile785 (488 per km)

What 245/45R17 means

245 is the section width in millimetres (9.6 in). 45 is the aspect ratio: the sidewall is 45% as tall as the tire is wide, which works out to 110.2 mm or 4.3 in. R17 is a radial tire for a 17-inch wheel.

Overall diameter is the wheel plus two sidewalls: 17 + 2 × 4.34 = 25.7 inches. These are the nominal dimensions every maker builds to; a real 245/45R17 can measure a few tenths of an inch differently by model and inflation.

Closest equivalent sizes

Common sizes within the usual 3% of 245/45R17's overall diameter. Confirm load index, speed rating and rim width before swapping.

SizeDiameterWidthChangeSpeedometer at 60
205/60R16 new wheels 25.7 in 8.1 in +0.0% really 60.0 mph
245/40R18 new wheels 25.7 in 9.6 in +0.1% really 60.1 mph
225/60R15 new wheels 25.6 in 8.9 in -0.2% really 59.9 mph
215/45R18 new wheels 25.6 in 8.5 in -0.2% really 59.9 mph
225/55R16 new wheels 25.7 in 8.9 in +0.2% really 60.1 mph
245/35R19 new wheels 25.8 in 9.6 in +0.3% really 60.2 mph

Speedometer if you switch to 205/60R16

Your speedometer stays calibrated for 245/45R17. With a taller tire you travel faster than it shows.

Speedometer readsTrue speed
30 mph30.0 mph
45 mph45.0 mph
55 mph55.0 mph
65 mph65.0 mph
75 mph75.0 mph
Compare 245/45R17 with any size →

Shop 245/45R17 tires

Check the load index and speed rating on your door-jamb placard before you buy, especially for LT tires used for towing.

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Frequently Asked Questions

A 245/45R17 tire is 25.7 inches (652 mm) tall overall. That is the 17-inch wheel plus two sidewalls of 4.3 inches each (45% of the 245 mm section width). Expect a real tire to measure within a few tenths of an inch of this, depending on the model and inflation.

The section width is 245 mm, or 9.6 inches, measured sidewall to sidewall on the recommended rim width. The tread itself is narrower than that. In flotation sizing, 245/45R17 is roughly a 25.7x9.6R17.

205/60R16 is the closest common size, at +0.0% overall diameter (25.7 in against 25.7 in). Most makers treat about 3% as the limit for a swap without speedometer or clearance problems, but always confirm load index, speed rating and wheel width before changing size.

About 785 revolutions per mile (488 per kilometre), from its 25.7-inch rolling diameter. Real-world figures run slightly higher because a loaded tire squats. This number is what your speedometer and odometer are calibrated against.

Last updated: October 2, 2026

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The full calculator compares up to three sizes with speedometer error, clearance change and a to-scale diagram.

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Other 17-inch sizes

205/40R17 205/50R17 205/55R17 215/45R17 215/50R17 215/55R17 215/60R17 215/65R17 225/45R17 225/50R17 225/55R17 225/60R17 225/65R17 235/45R17 235/55R17 235/60R17 235/65R17 235/70R17 235/80R17 245/40R17 245/65R17 245/70R17 245/75R17 255/60R17 255/65R17 255/70R17 255/75R17 265/65R17 265/70R17 275/65R17 275/70R17 285/70R17 285/75R17 315/70R17 235/50R17 255/40R17 275/60R17 305/65R17