315/30R18
Standard MetricFactory Specs, Physical Dimensions & Compatible Vehicle Applications
The 315/30R18 tire size features an overall diameter of 25.44 inches, a section width of 12.4 inches (315mm), and rotates 793 times per mile. It is a standard factory tire fitment on 4+ vehicle models including Porsche 911.
Physical Dimensions & Specs
Overall Diameter
25.44"
646.2 mmSection Width
315 mm
12.40" wideSidewall Height
3.72"
94.5 mm (30% aspect)Revolutions / Mile
793
Circumference: 79.93"Rim Diameter
18"
Wheel sizeRecommended Rim Width
7.9" - 11"
Optimal rim width rangeWhere to Buy & Install 315/30R18 Tires
Looking for 315/30R18 tires? Skip hauling tires in your car—choose direct delivery to a local certified shop or doorstep delivery:
Tire Rack
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Amazon Automotive
Fast doorstep shipping for DIYers or bringing to your own shop.
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Speedometer & Alternate Size Calculator
Testing an alternate size for your vehicle? Compare 315/30R18 against any proposed tire size below:
Visual Tire & Wheel Comparison
Speedometer Variance
| Indicated | Actual Speed | Diff |
|---|---|---|
| 20 mph | 23.2 mph | +3.2 mph |
| 30 mph | 34.9 mph | +4.9 mph |
| 45 mph | 52.3 mph | +7.3 mph |
| 60 mph | 69.7 mph | +9.7 mph |
| 75 mph | 87.2 mph | +12.2 mph |
| 90 mph | 104.6 mph | +14.6 mph |
Fender & Suspension Clearance
Flush fitment. Extends 17.7mm outwards. Check wheel arch clearance under full suspension compression.
Vehicles That Fit 315/30R18 (4+ Models)
Factory standard and optional vehicle fitments utilizing 315/30R18 tires: