What is the diameter of a 285/40R21 tire?

A 285/40R21 tire has an overall diameter of 29.98 inches (761.5mm).

How many revolutions per mile does a 285/40R21 tire make?

A 285/40R21 tire makes approximately 673 revolutions per mile.

What rim width is recommended for 285/40R21 tires?

The recommended wheel rim width for a 285/40R21 tire is 7.1" - 10".

285/40R21

Standard Metric

Factory Specs, Physical Dimensions & Compatible Vehicle Applications

Factory Spec Overview

The 285/40R21 tire size features an overall diameter of 29.98 inches, a section width of 11.2 inches (285mm), and rotates 673 times per mile. It is a standard factory tire fitment on 73+ vehicle models including Audi SQ7.

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Physical Dimensions & Specs

Overall Diameter

29.98"

761.5 mm

Section Width

285 mm

11.22" wide

Sidewall Height

4.49"

114.0 mm (40% aspect)

Revolutions / Mile

673

Circumference: 94.17"

Rim Diameter

21"

Wheel size

Recommended Rim Width

7.1" - 10"

Optimal rim width range

Where to Buy & Install 285/40R21 Tires

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Speedometer & Alternate Size Calculator

Testing an alternate size for your vehicle? Compare 285/40R21 against any proposed tire size below:

Popular Comparisons:

Tire 1 (Stock / Base)285/40R21

Section Width (mm)

Aspect Ratio (%)

Rim Diameter (in)

Wheel Width (in)

Offset ET (mm)

Overall Height:30.0"

Sidewall:4.5"

Revs/Mile:673

Tire 2 (New / Compare)245/60R18

Section Width (mm)

Aspect Ratio (%)

Rim Diameter (in)

Wheel Width (in)

Offset ET (mm)

Overall Height:29.6"

Sidewall:5.8"

Revs/Mile:682

Visual Tire & Wheel Comparison

Speedometer Variance

-1.3%At 60 mph reading, actual speed is 59.2 mph

Indicated	Actual Speed	Diff
20 mph	19.7 mph	-0.3 mph
30 mph	29.6 mph	-0.4 mph
45 mph	44.4 mph	-0.6 mph
60 mph	59.2 mph	-0.8 mph
75 mph	74.0 mph	-1.0 mph
90 mph	88.8 mph	-1.2 mph

Fender & Suspension Clearance

Fitment Status: MODERATE RISK

Flush fitment. Extends 17.7mm outwards. Check wheel arch clearance under full suspension compression.

Inner Strut Space:7.7mm LESS clearance

Outer Fender Push:Extends 17.7mm further out

Ride Height Delta:-0.20" lower ground clearance

Vehicles That Fit 285/40R21 (73+ Models)

Factory standard and optional vehicle fitments utilizing 285/40R21 tires:

Year	Make & Model	Trim / Variant	Lookup Specs
2020	Audi SQ7	Premium Plus	View 2020 SQ7 ›
2020	Audi SQ7	Prestige	View 2020 SQ7 ›
2021	Audi SQ7	Prestige	View 2021 SQ7 ›
2021	Audi SQ7	Premium Plus	View 2021 SQ7 ›
2022	Audi SQ7	Premium Plus	View 2022 SQ7 ›
2022	Audi SQ7	Prestige	View 2022 SQ7 ›
2023	Audi SQ7	Premium Plus	View 2023 SQ7 ›
2023	Audi SQ7	Prestige	View 2023 SQ7 ›
2024	Audi Q7	Prestige	View 2024 Q7 ›
2024	Audi SQ7	Premium Plus	View 2024 SQ7 ›
2024	Audi SQ7	Prestige	View 2024 SQ7 ›
2025	Audi Q7	Prestige	View 2025 Q7 ›
2025	Audi SQ6 e-tron	Prestige	View 2025 SQ6 e-tron ›
2025	Audi SQ7	Premium Plus	View 2025 SQ7 ›
2025	Audi SQ7	Prestige	View 2025 SQ7 ›
2019	Porsche Cayenne	Base	View 2019 Cayenne ›
2019	Porsche Cayenne	S	View 2019 Cayenne ›
2019	Porsche Cayenne	Turbo	View 2019 Cayenne ›
2019	Porsche Cayenne	E-Hybrid	View 2019 Cayenne ›
2020	Porsche Cayenne	Base, 4D Utility Wagon	View 2020 Cayenne ›
2020	Porsche Cayenne	Base, 4D Utility Coupe	View 2020 Cayenne ›
2020	Porsche Cayenne	E-Hybrid, 4D Utility Wagon	View 2020 Cayenne ›
2020	Porsche Cayenne	E-Hybrid, 4D Utility Coupe	View 2020 Cayenne ›
2020	Porsche Cayenne	S, 4D Utility Coupe	View 2020 Cayenne ›
2020	Porsche Cayenne	S, 4D Utility Wagon	View 2020 Cayenne ›
2020	Porsche Cayenne	Turbo, 4D Utility Coupe	View 2020 Cayenne ›
2020	Porsche Cayenne	Turbo, 4D Utility Wagon	View 2020 Cayenne ›
2020	Porsche Cayenne	Turbo S E-Hybrid, 4D Utility Wagon	View 2020 Cayenne ›
2020	Porsche Cayenne	Turbo S E-Hybrid, 4D Utility Coupe	View 2020 Cayenne ›
2021	Porsche Cayenne	Base, 4D Utility Coupe	View 2021 Cayenne ›
2021	Porsche Cayenne	Base, 4D Utility Wagon	View 2021 Cayenne ›
2021	Porsche Cayenne	E-Hybrid, 4D Utility Coupe	View 2021 Cayenne ›
2021	Porsche Cayenne	E-Hybrid, 4D Utility Wagon	View 2021 Cayenne ›
2021	Porsche Cayenne	GTS, 4D Utility Coupe	View 2021 Cayenne ›
2021	Porsche Cayenne	GTS, 4D Utility Wagon	View 2021 Cayenne ›
2021	Porsche Cayenne	S, 4D Utility Wagon	View 2021 Cayenne ›
2021	Porsche Cayenne	Turbo S E-Hybrid, 4D Utility Coupe	View 2021 Cayenne ›
2021	Porsche Cayenne	Turbo S E-Hybrid, 4D Utility Wagon	View 2021 Cayenne ›
2021	Porsche Cayenne	Turbo, 4D Utility Coupe	View 2021 Cayenne ›
2021	Porsche Cayenne	Turbo, 4D Utility Wagon	View 2021 Cayenne ›
2021	Porsche Cayenne	S, 4D Utility Coupe	View 2021 Cayenne ›
2022	Porsche Cayenne	Base, 4D Utility Coupe	View 2022 Cayenne ›
2022	Porsche Cayenne	Base, 4D Utility Wagon	View 2022 Cayenne ›
2022	Porsche Cayenne	E-Hybrid, 4D Utility Coupe	View 2022 Cayenne ›
2022	Porsche Cayenne	E-Hybrid, 4D Utility Wagon	View 2022 Cayenne ›
2022	Porsche Cayenne	GTS, 4D Utility Coupe	View 2022 Cayenne ›
2022	Porsche Cayenne	GTS, 4D Utility Wagon	View 2022 Cayenne ›
2022	Porsche Cayenne	Platinum Edition, 4D Utility Coupe	View 2022 Cayenne ›
2022	Porsche Cayenne	Platinum Edition, 4D Utility Wagon	View 2022 Cayenne ›
2022	Porsche Cayenne	S, 4D Utility Coupe	View 2022 Cayenne ›
2022	Porsche Cayenne	S, 4D Utility Wagon	View 2022 Cayenne ›
2022	Porsche Cayenne	Turbo S E-Hybrid, 4D Utility Coupe	View 2022 Cayenne ›
2022	Porsche Cayenne	Turbo S E-Hybrid, 4D Utility Wagon	View 2022 Cayenne ›
2022	Porsche Cayenne	Turbo, 4D Utility Coupe	View 2022 Cayenne ›
2022	Porsche Cayenne	Turbo, 4D Utility Wagon	View 2022 Cayenne ›
2023	Porsche Cayenne	Base, 4D Utility Coupe	View 2023 Cayenne ›
2023	Porsche Cayenne	Base, 4D Utility Wagon	View 2023 Cayenne ›
2023	Porsche Cayenne	E-Hybrid Platinum Edition, 4D Utility Coupe	View 2023 Cayenne ›
2023	Porsche Cayenne	E-Hybrid Platinum Edition, 4D Utility Wagon	View 2023 Cayenne ›
2023	Porsche Cayenne	E-Hybrid, 4D Utility Coupe	View 2023 Cayenne ›
2023	Porsche Cayenne	E-Hybrid, 4D Utility Wagon	View 2023 Cayenne ›
2023	Porsche Cayenne	GTS, 4D Utility Coupe	View 2023 Cayenne ›
2023	Porsche Cayenne	Platinum Edition, 4D Utility Coupe	View 2023 Cayenne ›
2023	Porsche Cayenne	Platinum Edition, 4D Utility Wagon	View 2023 Cayenne ›
2023	Porsche Cayenne	S Platinum Edition, 4D Utility Coupe	View 2023 Cayenne ›
2023	Porsche Cayenne	GTS, 4D Utility Wagon	View 2023 Cayenne ›
2023	Porsche Cayenne	S Platinum Edition, 4D Utility Wagon	View 2023 Cayenne ›
2023	Porsche Cayenne	S, 4D Utility Coupe	View 2023 Cayenne ›
2023	Porsche Cayenne	S, 4D Utility Wagon	View 2023 Cayenne ›
2023	Porsche Cayenne	Turbo S E-Hybrid, 4D Utility Coupe	View 2023 Cayenne ›
2023	Porsche Cayenne	Turbo S E-Hybrid, 4D Utility Wagon	View 2023 Cayenne ›
2023	Porsche Cayenne	Turbo, 4D Utility Coupe	View 2023 Cayenne ›
2023	Porsche Cayenne	Turbo, 4D Utility Wagon	View 2023 Cayenne ›