What Size Rotors Are on a 2018 Audi S5?

The 2018 Audi S5 typically uses approximately 350 mm (13.8 in) front brake rotors and 330 mm (13.0 in) rear brake rotors on most non-ceramic, factory configurations, but exact sizing can vary slightly by market and specific package, so confirming via VIN, build sheet, or direct measurement is strongly recommended.

Understanding the 2018 Audi S5 Brake Rotor Sizes

The question of rotor size on a 2018 Audi S5 is more nuanced than it may appear. While there are common “standard” sizes used on these models, factors such as trim (Coupe vs Sportback vs Cabriolet), optional performance packages, and regional specifications can influence the exact front and rear rotor diameters. Owners often seek this information to purchase replacement rotors, upgrade braking components, or verify fitment for aftermarket wheels and calipers.

Factory Rotor Sizes: Typical Dimensions for the 2018 Audi S5

Below is an overview of the rotor sizes most commonly associated with the 2018 Audi S5 equipped with the standard high-performance steel braking system, not including special-order or aftermarket kits. This information helps frame what’s “normal” for most owners while acknowledging that there can be exceptions.

• Front rotors (most 2018 S5 models): Approximately 350 mm (13.8 in) diameter, ventilated
• Rear rotors (most 2018 S5 models): Approximately 330 mm (13.0 in) diameter, ventilated
• Typical thickness range (front): Around 30–34 mm new (varies slightly by supplier/spec)
• Typical thickness range (rear): Around 20–22 mm new (varies slightly by supplier/spec)
• Type of brakes: Steel rotors with high-performance calipers; ceramic brakes were not a mainstream option on the S5 in most markets

These figures reflect commonly referenced OEM specifications for the B9-generation 2018 Audi S5. However, production changes, region-specific components, and dealer-installed performance upgrades mean owners should treat these as a baseline, not a substitute for VIN-verified data.

Why Rotor Size Can Vary on the Same Model Year

Even within a single model year, rotor sizes can differ due to equipment packages and regional options. Understanding the factors that influence brake hardware can protect you from ordering the wrong parts and can guide you in planning upgrades.

Trim Level and Body Style Differences

Different body styles of the 2018 S5—Coupe, Sportback, and Cabriolet—share the same basic platform and engine, but curb weight, target buyer, and market configuration can influence brake equipment. In practice, most 2018 S5 variants use the same nominal rotor diameters, yet optional equipment or country-specific homologation can introduce variations, especially in thickness or specific part numbers, even if the diameter remains the same.

Performance and Appearance Packages

Factory or dealer-installed performance packages can also impact the rotor setup. While the S5 generally comes with strong brakes from the factory, some markets offered sport or “S line” enhancements, and dealers sometimes installed larger calipers or performance rotors as part of accessory packs. This is not as common as on RS models, but owners of used cars should never assume the current setup is stock.

How to Confirm the Exact Rotor Size on Your Specific S5

Because catalog entries, online forums, and generic parts listings can be inconsistent or incomplete, the most reliable approach is to confirm the rotor size tied to your exact vehicle identity. The following methods are the most dependable ways to verify rotor dimensions before ordering or upgrading parts.

1. Check via VIN with an Audi dealer: Provide your Vehicle Identification Number to an Audi service department; they can pull the exact OEM rotor part numbers and specifications originally installed on your car.
2. Use official parts catalogs: Online parts databases or ETKA-based catalogs can decode your VIN and list precise front and rear rotor diameters, thickness, and compatible alternatives.
3. Inspect existing rotors directly: If the wheels are off, you can measure rotor diameter and thickness with a tape measure and caliper, noting stamped part numbers on the rotor hat where visible.
4. Match part numbers from service history: Review invoices from prior brake work; OEM or high-quality aftermarket invoices often list exact rotor size and part numbers.
5. Consult reputable aftermarket suppliers: Major rotor manufacturers and performance brake companies often maintain detailed application guides; cross-referencing your VIN and trim can confirm rotor sizing.

Using at least one VIN-based method, and ideally cross-checking with a physical measurement, minimizes the risk of fitment issues, especially on vehicles that may have been modified by previous owners.

Why Rotor Size Matters for Performance and Safety

Rotor diameter and thickness directly affect braking performance, heat capacity, and overall driving feel. On a performance-oriented car like the 2018 Audi S5, these factors are crucial, especially for spirited driving or repeated high-speed stops.

Heat Management and Fade Resistance

Larger, thicker, ventilated rotors can absorb and dissipate more heat, reducing the risk of brake fade under hard use. The S5’s approximately 350 mm front rotors are designed to handle the turbocharged V6’s performance, helping keep braking consistent during aggressive acceleration and repeated stops. Undersized or incorrect rotors can overheat faster, lengthen stopping distances, and damage pads and calipers.

Compatibility with Calipers and Wheels

Rotor size must match the caliper bracket and wheel clearance. A rotor that is too large may not physically fit inside the wheel or line up with the caliper, while one that is too small can reduce the effective braking surface and compromise safety. The factory S5 rotor dimensions are calibrated to work with its multi-piston calipers and OEM wheel diameters; any changes should be planned as a coordinated system upgrade.

Summary

Most 2018 Audi S5 models are equipped from the factory with approximately 350 mm (13.8 in) ventilated front brake rotors and 330 mm (13.0 in) ventilated rear rotors in steel, providing strong, balanced braking for a high-performance daily driver. However, trim-level nuances, regional specs, and potential aftermarket modifications mean you should confirm the exact sizes for your specific car through its VIN, an Audi parts catalog, or direct measurement before purchasing replacement or upgraded rotors.