245/40R17 Tire Size

All You Need to Know About 245/40R17 Tires

245/40R17 tires are 245 mm wide, with a 40% aspect ratio and a 17-inch wheel diameter, resulting in an overall diameter of 24.7 inches and a sidewall height of 3.86 inches.

This page focuses on the 245/40R17 size and its dimensional and performance characteristics. For passenger load standard specifications and pressure-related differences, see P245/40R17 tires.

The 245/40R17 size is positioned in the low-profile performance category, where increased width is combined with a short sidewall to improve grip, lateral stability, and steering response.

Relative to a narrower size such as 235/40R17, the 245/40R17 maintains a similar sidewall profile but adds section width. That change increases the contact patch and can improve traction under load, while also requiring more space within the wheel well.

In some listings, this size may appear with a P-prefix (P245/40R17), indicating a passenger load standard. While external dimensions remain unchanged, load capacity and pressure behavior depend on how the tire is rated rather than the size itself.

245/40R17 Size Quick Specs

• Approved rim width range: 8.0–9.5"
• Width: 245 mm
• Sidewall height: 98.00 mm
• Overall diameter: 2≈24.7"
• Wheel diameter: 17 in

Note: The calculated overall diameter of 245/40R17 is ≈24.7 inches. Minor variation may occur depending on tread depth and the manufacturer's construction.

245/40R17 Common Vehicle Fitment

245/40R17 is typically used on performance-oriented sedans and coupes equipped with wider wheels. In the U.S. market, it appears more often in upgraded or sport configurations than as a base OEM fitment. Common applications include:

• BMW 3 Series (performance trims)
• Ford Mustang (selected configurations)
• Subaru WRX (performance builds)
• Nissan 370Z (specific setups)

Because 245/40R17 combines increased width with a short sidewall, it places greater demand on wheel width and available clearance. Before using 245/40R17 as a replacement, both inner clearance to suspension components and outer fender space should be verified alongside the approved rim width range.

245/40R17 Dimensions in Inches

The 245/40R17 tire size measures approximately 9.65 inches in width, 24.7 inches in overall diameter, and has a sidewall height of about 3.86 inches.

The short sidewall limits vertical flex, which improves steering precision and responsiveness under load. At the same time, the wider section increases grip potential during cornering, while reducing clearance margins compared to narrower sizes.

245/40R17 in Inches: All Measurements

• Overall diameter: ≈24.7"
• Width: 9.65"
• Sidewall height: 3.86"
• Wheel diameter: 17"
• Circumference: 77.66" (≈77.7")

Comparison of 245/40R17 With Similar Tire Sizes

Within low-profile 17-inch performance sizing, 245/40R17 aligns with wider configurations that prioritize grip. The closest comparisons are 235/40R17 as a narrower alternative and 245/45R17 as a taller option.

Difference Between 245/40R17 and 235/40R17

• Width: 10 mm narrower
• Diameter: ≈0.32" (≈1.3%) smaller

Since the difference remains within ±3% diameter range, 245/40R17 and 235/40R17 sizes are generally interchangeable from a rolling-diameter standpoint. The primary change is section width, which affects contact patch and clearance.

Difference Between 245/40R17 and 245/45R17

• Width: identical
• Diameter: ≈0.96" (≈3.9%) larger

This exceeds the ±3% threshold, meaning 245/40R17 and 245/45R17 sizes are not directly interchangeable due to changes in ride height, gearing, and clearance.