What is the diameter of a 315/30R21 tire?

A 315/30R21 tire has an overall diameter of 28.44 inches (722.4mm).

How many revolutions per mile does a 315/30R21 tire make?

A 315/30R21 tire makes approximately 709 revolutions per mile.

What rim width is recommended for 315/30R21 tires?

The recommended wheel rim width for a 315/30R21 tire is 7.9" - 11".

315/30R21

Standard Metric

Factory Specs, Physical Dimensions & Compatible Vehicle Applications

Factory Spec Overview

The 315/30R21 tire size features an overall diameter of 28.44 inches, a section width of 12.4 inches (315mm), and rotates 709 times per mile. It is a standard factory tire fitment on 65+ vehicle models including Porsche Panamera.

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Physical Dimensions & Specs

Overall Diameter

28.44"

722.4 mm

Section Width

315 mm

12.40" wide

Sidewall Height

3.72"

94.5 mm (30% aspect)

Revolutions / Mile

709

Circumference: 89.35"

Rim Diameter

21"

Wheel size

Recommended Rim Width

7.9" - 11"

Optimal rim width range

Speedometer & Alternate Size Calculator

Testing an alternate size for your vehicle? Compare 315/30R21 against any proposed tire size below:

Popular Comparisons:

Tire 1 (Stock / Base)315/30R21

Section Width (mm)

Aspect Ratio (%)

Rim Diameter (in)

Wheel Width (in)

Offset ET (mm)

Overall Height:28.4"

Sidewall:3.7"

Revs/Mile:709

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

+4.0%At 60 mph reading, actual speed is 62.4 mph

Indicated	Actual Speed	Diff
20 mph	20.8 mph	+0.8 mph
30 mph	31.2 mph	+1.2 mph
45 mph	46.8 mph	+1.8 mph
60 mph	62.4 mph	+2.4 mph
75 mph	78.0 mph	+3.0 mph
90 mph	93.6 mph	+3.6 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:+0.57" ground clearance

Vehicles That Fit 315/30R21 (65+ Models)

Factory standard and optional vehicle fitments utilizing 315/30R21 tires:

Year	Make & Model	Trim / Variant	Lookup Specs
2018	Porsche Panamera	Turbo S E-Hybrid	View 2018 Panamera ›
2018	Porsche Panamera	Turbo S E-Hybrid Executive	View 2018 Panamera ›
2018	Porsche Panamera	Turbo S E-Hybrid Sport Turismo	View 2018 Panamera ›
2019	Porsche Panamera	Turbo S E-Hybrid	View 2019 Panamera ›
2019	Porsche Panamera	Turbo S E-Hybrid Executive	View 2019 Panamera ›
2019	Porsche Panamera	Turbo S E-Hybrid Sport Turismo	View 2019 Panamera ›
2020	Porsche Panamera	4	View 2020 Panamera ›
2020	Porsche Panamera	4 E-Hybrid	View 2020 Panamera ›
2020	Porsche Panamera	Base	View 2020 Panamera ›
2020	Porsche Panamera	Turbo S E-Hybrid	View 2020 Panamera ›
2020	Porsche Panamera	Turbo S E-Hybrid Sport Turismo	View 2020 Panamera ›
2020	Porsche Panamera	Turbo S E-Hybrid Executive	View 2020 Panamera ›
2021	Porsche 911	Turbo S, 2D Coupe	View 2021 911 ›
2021	Porsche 911	Turbo, 2D Coupe	View 2021 911 ›
2021	Porsche 911	Turbo, 2D Convertible	View 2021 911 ›
2021	Porsche 911	Turbo S, 2D Convertible	View 2021 911 ›
2021	Porsche Panamera	Turbo S E-Hybrid Executive	View 2021 Panamera ›
2021	Porsche Panamera	Turbo S E-Hybrid	View 2021 Panamera ›
2021	Porsche Panamera	Turbo S	View 2021 Panamera ›
2021	Porsche Panamera	Turbo S E-Hybrid Sport Turismo	View 2021 Panamera ›
2021	Porsche Panamera	Turbo S Executive	View 2021 Panamera ›
2021	Porsche Panamera	Turbo S Sport Turismo	View 2021 Panamera ›
2022	Porsche 911	GT3, Automatic DCT Trans	View 2022 911 ›
2022	Porsche 911	GT3, Standard Trans	View 2022 911 ›
2022	Porsche 911	Turbo S, 2D Convertible	View 2022 911 ›
2022	Porsche 911	Turbo S, 2D Coupe	View 2022 911 ›
2022	Porsche 911	Turbo, 2D Convertible	View 2022 911 ›
2022	Porsche 911	Turbo, 2D Coupe	View 2022 911 ›
2022	Porsche Panamera	4 E-Hybrid Platinum Edition	View 2022 Panamera ›
2022	Porsche Panamera	4 Platinum Edition	View 2022 Panamera ›
2022	Porsche Panamera	Platinum Edition	View 2022 Panamera ›
2022	Porsche Panamera	Turbo S	View 2022 Panamera ›
2022	Porsche Panamera	Turbo S E-Hybrid	View 2022 Panamera ›
2022	Porsche Panamera	Turbo S E-Hybrid Executive	View 2022 Panamera ›
2022	Porsche Panamera	Turbo S E-Hybrid Sport Turismo	View 2022 Panamera ›
2022	Porsche Panamera	Turbo S Executive	View 2022 Panamera ›
2022	Porsche Panamera	Turbo S Sport Turismo	View 2022 Panamera ›
2023	Porsche 911	GT3 Touring Package, Automatic DCT Trans	View 2023 911 ›
2023	Porsche 911	GT3 Touring Package, Standard Trans	View 2023 911 ›
2023	Porsche 911	GT3, Automatic DCT Trans	View 2023 911 ›
2023	Porsche 911	GT3, Standard Trans	View 2023 911 ›
2023	Porsche 911	Sport Classic	View 2023 911 ›
2023	Porsche 911	Turbo S, 2D Convertible	View 2023 911 ›
2023	Porsche 911	Turbo S, 2D Coupe	View 2023 911 ›
2023	Porsche 911	Turbo, 2D Convertible	View 2023 911 ›
2023	Porsche 911	Turbo, 2D Coupe	View 2023 911 ›
2023	Porsche Panamera	4 E-Hybrid Platinum Edition	View 2023 Panamera ›
2023	Porsche Panamera	4 Platinum Edition	View 2023 Panamera ›
2023	Porsche Panamera	Platinum Edition	View 2023 Panamera ›
2023	Porsche Panamera	Turbo S	View 2023 Panamera ›
2023	Porsche Panamera	Turbo S E-Hybrid	View 2023 Panamera ›
2023	Porsche Panamera	Turbo S E-Hybrid Executive	View 2023 Panamera ›
2023	Porsche Panamera	Turbo S Executive	View 2023 Panamera ›
2023	Porsche Panamera	Turbo S Sport Turismo	View 2023 Panamera ›
2024	Porsche 911	GT3 Touring Package, Automatic DCT Trans	View 2024 911 ›
2024	Porsche 911	GT3 Touring Package, Standard Trans	View 2024 911 ›
2024	Porsche 911	GT3, Automatic DCT Trans	View 2024 911 ›
2024	Porsche 911	GT3, Standard Trans	View 2024 911 ›
2024	Porsche 911	S/T	View 2024 911 ›
2024	Porsche 911	Turbo S, 2D Coupe	View 2024 911 ›
2024	Porsche 911	Turbo, 2D Convertible	View 2024 911 ›
2024	Porsche 911	Turbo, 2D Coupe	View 2024 911 ›
2024	Porsche 911	Turbo S, 2D Convertible	View 2024 911 ›
2025	Porsche 911	GT3, Standard Trans	View 2025 911 ›
2025	Porsche 911	Turbo, 2D Convertible	View 2025 911 ›