315/30R21
Standard MetricFactory Specs, Physical Dimensions & Compatible Vehicle Applications
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.
Physical Dimensions & Specs
Overall Diameter
28.44"
722.4 mmSection Width
315 mm
12.40" wideSidewall Height
3.72"
94.5 mm (30% aspect)Revolutions / Mile
709
Circumference: 89.35"Rim Diameter
21"
Wheel sizeRecommended Rim Width
7.9" - 11"
Optimal rim width rangeWhere to Buy & Install 315/30R21 Tires
Looking for 315/30R21 tires? Skip hauling tires in your car—choose direct delivery to a local certified shop or doorstep delivery:
Tire Rack
Free shipping directly to over 10,000+ certified local installers.
- ✓Delivered to local installer (Firestone, Discount Tire & local shops)
- ✓Mobile installation available — mount & balance right in your driveway
- ✓Free 2-year road hazard warranty on most eligible tire models
Amazon Automotive
Fast doorstep shipping for DIYers or bringing to your own shop.
- ✓Prime doorstep shipping for home garages or spares
- ✓Huge range of budget and specialty tire sizes in stock
- ✓Ideal if you have a local independent mechanic you prefer
As an affiliate for Tire Rack and Amazon, we earn from qualifying purchases at no extra cost to you.
Speedometer & Alternate Size Calculator
Testing an alternate size for your vehicle? Compare 315/30R21 against any proposed tire size below:
Visual Tire & Wheel Comparison
Speedometer Variance
| 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
Flush fitment. Extends 17.7mm outwards. Check wheel arch clearance under full suspension compression.
Vehicles That Fit 315/30R21 (65+ Models)
Factory standard and optional vehicle fitments utilizing 315/30R21 tires: