305/30R20 Tire Size Specifications
This tire size 305/30R20 fits 4 vehicles in our database.
Everything to know about the 305/30R20 tire size
Size geometry
A 305/30R20 tire has a 305mm section width and a 30% aspect ratio, mounted on a 20-inch rim. Sidewall height works out to 91.5mm (3.60") and overall outside diameter is 691.0mm (27.20"). At highway speed the tire completes about 461 revolutions per kilometre â your speedometer and odometer were calibrated against this number.
Direct substitute sizes
If 305/30R20 is unavailable, the closest same-diameter substitutes on the same rim are 295/31R20 and 315/29R20. Both keep your speedometer reading within 1% â safe for daily use, ABS, and stability control. Always verify load and speed ratings before swapping.
Plus / minus sizing options
For a 305/30R20 you can upsize to 315/25R21 (plus-one) to fit a larger wheel without changing the speedometer reading, or downsize to 295/35R19 (minus-one) for a softer ride or winter setup. Both stay inside the Âą3% diameter tolerance that ABS and TPMS systems expect.
Vehicle compatibility
4 vehicles in our database run the 305/30R20 tire size from the factory. Aftermarket fitment depends on rim width, offset, and clearance â match these specs to your wheel before purchasing tires.