345/40R17 Tire Size

All You Need to Know About 345/40R17 Tires

345/40R17 tires are 345 mm wide, with a 40% aspect ratio and a 17-inch wheel diameter, producing an overall diameter of 27.9 inches and a sidewall height of 5.4 inches.

The 345/40R17 is one of the widest standard passenger-format tires produced in a 17-inch diameter. At 345mm of section width and a 40-series profile, the tire's design emphasis is unambiguously on maximizing rear contact area - a priority associated with high-power drag racing applications and select exotic builds where rear traction is the primary variable being managed. The 40-series profile adds more sidewall height than the extreme 35-series widths found on some high-end sports cars, providing a modest cushioning capacity without meaningfully softening the casing's lateral rigidity.

Compared to the 335/40R17, the 345/40R17 adds 10mm of section width while producing only a ≈0.32-inch (≈1.2%) increase in overall diameter - well within the ±3% interchangeability threshold. Against the 345/35R17, the 40-series profile increases sidewall height substantially enough that the overall diameter difference (≈1.36 inches / ≈4.9%) exceeds the ±3% limit, and the two sizes are not direct substitutes.

345/40R17 Size Quick Specs

• Approved rim width range: 11.5-13.5"
• Measured/Recommended Rim: 12.0"
• Width: 345 mm
• Sidewall height: 138.0 mm
• Overall diameter: 27.9"
• Wheel diameter: 17 in

Note: The calculated overall diameter of 345/40R17 is ≈27.9 inches. Variations across tread designs and casing constructions affect the measured figure. The wide approved rim range (11.5–13.5") significantly affects sidewall stance, section width, and contact patch shape. Learn more about Rim Width Ranges and Limits.

345/40R17 Common Vehicle Fitment

345/40R17 size is most frequently selected for drag racing builds and specialty performance applications where the rear tire width is being maximized beyond factory limits. Platforms where this size has been applied in aftermarket or competition configurations include:

• Dodge Viper (aftermarket rear fitment, beyond the factory 335/35R17 specification)
• Rear-wheel-drive muscle cars and purpose-built drag vehicles with custom suspension geometry

Because 345/40R17 is not a production OEM size in the U.S. market, fitment requires custom validation: wheel well clearance, suspension geometry throughout articulation range, approved rim width, and brake system compatibility all need individual confirmation before this tire is installed on any platform.

345/40R17 Dimensions in Inches

The 345/40R17 tire size measures approximately 13.6 inches in width, 27.9 inches in overall diameter, and has a sidewall height of about 5.4 inches.

In the 345/40R17 size, the combination of 13.6-inch width and 5.4-inch sidewall height on a 17-inch rim produces one of the largest footprints achievable in a radial tire at this wheel size. More sidewall height than a 35-series equivalent means the casing has some vertical compliance - enough to maintain contact over minor surface variations at launch - while the extreme width ensures the maximum possible patch of rubber contacts the traction surface. This is the balance that makes the 345/40R17 relevant to both drag strip use and road-use exotics, where sheer mechanical grip is engineered into the platform.

345/40R17 in Inches: All Measurements

• Overall diameter: ≈27.9"
• Width: 13.6"
• Sidewall height: 5.4"
• Wheel diameter: 17"
• Circumference: ≈87.6"

Comparison of 345/40R17 With Similar Tire Sizes

345/40R17 sits between the 335/40R17 as a narrower equivalent and the 345/35R17 as a shorter-profile variant that carries the same width. These are the two most relevant comparisons for evaluating cross-reference options.

Difference Between 345/40R17 and 335/40R17 Tire Sizes

The 335/40R17 is narrower while maintaining a similar overall diameter:

• Width: 335/40R17 is 10 mm narrower
• Overall diameter: 335/40R17 is ≈0.32 inches (≈1.2%) smaller than 345/40R17

335/40R17 and 345/40R17 sizes fall within the ±3% compatibility window and are generally interchangeable in rolling circumference terms. The 335/40R17 reduces footprint width by 10mm, which affects traction output on high-power applications - a meaningful distinction even at that scale in drag or track contexts.

Difference Between 345/40R17 and 345/35R17 Tire Sizes

The 345/35R17 carries the same width but with a shorter sidewall:

• Width: identical at 345 mm
• Overall diameter: 345/35R17 is ≈1.36 inches (≈4.9%) smaller than 345/40R17

This difference significantly exceeds the ±3% threshold, meaning 345/35R17 and 345/40R17 sizes are not interchangeable. The 345/35R17 substantially lowers ride height and reduces sidewall compliance, which has measurable effects on launch behavior and suspension geometry. Before making any switch, it is worth understanding how the 3% rule works in practice and what else to verify when changing tire size.