305/40R20
Standard MetricFactory Specs, Physical Dimensions & Compatible Vehicle Applications
Factory Spec Overview
The 305/40R20 tire size features an overall diameter of 29.61 inches, a section width of 12.0 inches (305mm), and rotates 681 times per mile. It is a standard factory tire fitment on 27+ vehicle models including Porsche Cayenne.
Physical Dimensions & Specs
Overall Diameter
29.61"
752.1 mmSection Width
305 mm
12.01" wideSidewall Height
4.8"
121.9 mm (40% aspect)Revolutions / Mile
681
Circumference: 93.01"Rim Diameter
20"
Wheel sizeRecommended Rim Width
7.6" - 10.7"
Optimal rim width rangeSpeedometer & Alternate Size Calculator
Testing an alternate size for your vehicle? Compare 305/40R20 against any proposed tire size below:
Popular Comparisons:
Tire 1 (Stock / Base)305/40R20
Overall Height:29.6"
Sidewall:4.8"
Revs/Mile:681
Tire 2 (New / Compare)245/60R18
Overall Height:29.6"
Sidewall:5.8"
Revs/Mile:682
Visual Tire & Wheel Comparison
Speedometer Variance
-0.1%At 60 mph reading, actual speed is 59.9 mph
| Indicated | Actual Speed | Diff |
|---|---|---|
| 20 mph | 20.0 mph | -0.0 mph |
| 30 mph | 30.0 mph | -0.0 mph |
| 45 mph | 45.0 mph | -0.0 mph |
| 60 mph | 59.9 mph | -0.1 mph |
| 75 mph | 74.9 mph | -0.1 mph |
| 90 mph | 89.9 mph | -0.1 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:-0.02" lower ground clearance
Vehicles That Fit 305/40R20 (27+ Models)
Factory standard and optional vehicle fitments utilizing 305/40R20 tires: