255/40R17 Tire Size

All You Need to Know About 255/40R17 Tires

255/40R17 tires are 255 mm wide, with a 40% aspect ratio and a 17-inch wheel diameter, producing an overall diameter of 25.0 inches and a sidewall height of 4.02 inches.

The 255/40R17 size falls into the low-profile performance category, where a wide tread and shorter sidewall are used to reduce sidewall flex, sharpen steering response, and support higher lateral stability than taller 17-inch alternatives.

Compared with taller sizes such as 255/45R17, the 255/40R17 reduces both sidewall height and overall diameter. That lowers the tire’s vertical compliance and increases revolutions per mile, which changes effective gearing and slightly lowers ride height.

255/40R17 Size Quick Specs

• Approved rim width range: 8.5–10.0"
• Optimal measured rim width: 9"
• Width: 255 mm
• Sidewall height: 102.0 mm
• Overall diameter: 25.0"
• Wheel diameter: 17 in

Note: The calculated overall diameter of 255/40R17 is ≈25.0 inches. Minor variation (+/-1%) may occur depending on tread depth and casing design rather than the nominal size itself. Mounting this tire within its approved 8.5–10.0" rim width range also changes section shape and sidewall stance, though it does not alter the nominal diameter. Learn more about Rim Width Ranges and Limits.

255/40R17 Common Vehicle Fitment

255/40R17 appears mainly on performance-oriented rear-axle or staggered-wheel applications rather than on broad comfort-focused fitments. Common U.S.-market references include:

• BMW 3 Series (2005–2013, selected rear fitments), 5 Series (1988–2004, selected configurations), 7 Series (1998–2000, selected trims); 
• Nissan 300ZX (1990–1996, selected fitments)
• Acura: NSX (1994–2005)
• Audi: A6/S6 (1994–2005)
• Honda: S2000 (2006–2009)
• Mazda: RX-7 (1992–2003)
• Mercedes-Benz: E-Class Coupé/Cabriolet (2009–2017)
• Nissan: 300ZX (1990–1996)
• Porsche: 911 (1989–2006), 928, 944, 968, Boxster (1996–2004)
• Toyota: Supra (1986–2002) 

Because the 255/40R17 size is frequently used in staggered setups, 255/40R17 should be treated as axle- and trim-specific rather than as a universal platform size. Wheel width, offset, and rear-clearance limits matter as much as the nominal tire size itself.

255/40R17 Dimensions in Inches

The 255/40R17 tire size is approximately 10.04 inches wide, 25.0 inches tall overall, and has a sidewall height of about 4.02 inches.

The defining characteristic of the 255/40R17 size is its short sidewall relative to its width. At just over 4 inches, it limits sidewall deformation more than taller 45-series and 50-series alternatives, which improves steering precision and cornering support but transmits more road input into the suspension.

255/40R17 in Inches: All Measurements

• Overall diameter: ≈25.0"
• Width: 10.04"
• Sidewall height: 4.02"
• Wheel diameter: 17"
• Circumference: ≈78.64" (≈78.6")

Most Recommended 255/40R17 Tires

Best tires in 255/40R17 size include:

• 255/40R17 max-performance summer tires: Continental ExtremeContact Sport 02
• Ultra-high-performance tires 255/40R17: Continental ExtremeContact DWS06 Plus
• Track-capable tires 255 40r17: Toyo Proxes R888R
• 255/40R17 set of 4 (value-focused options): General G-Max RS

Comparison of 255/40R17 With Similar Tire Sizes

255/40R17 sits in the lower-profile part of the 17-inch range, where width is prioritized without moving into a taller sidewall configuration. The most relevant comparisons are with 255/45R17 as the taller counterpart and 265/40R17 as a wider alternative that stays close in overall diameter.

Difference Between 255/40R17 and 255/45R17 Tire Sizes

The 255/45R17 is taller while maintaining the same width:

• Width: identical at 255 mm
• Overall diameter: 255/45R17 is ≈1.00 inches (≈4.0%) larger than 255/40R17

This difference exceeds the ±3% threshold, so the 255/45R17 and 255/40R17 sizes are not directly interchangeable from a rolling-diameter standpoint. The taller 255/45R17 adds sidewall height and ride height, while 255/40R17 keeps a lower profile with less deflection under load.

Difference Between 255/40R17 and 265/40R17 Tire Sizes

The 265/40R17 is wider and slightly taller:

• Width: 265/40R17 is 10 mm wider
• Overall diameter: 265/40R17 is ≈0.31 inches (≈1.3%) larger than 255/40R17

The difference remains within the ±3% range, so 265/40R17 and 255/40R17 sizes are generally interchangeable from a diameter perspective. The main change is the added width, which affects fitment space, approved rim width, and the size of the contact patch under load.

Before making any switch from or to 265/40R17 size, it is worth understanding how the 3% rule works in practice and what else to verify when changing tire size.