315/51R21 Tire Size Specifications
This tire size 315/51R21 fits 0 vehicles in our database.
Everything to know about the 315/51R21 tire size
Size geometry
A 315/51R21 tire has a 315mm section width and a 51% aspect ratio, mounted on a 21-inch rim. Sidewall height works out to 160.7mm (6.32") and overall outside diameter is 854.7mm (33.65"). At highway speed the tire completes about 372 revolutions per kilometre â your speedometer and odometer were calibrated against this number.
Direct substitute sizes
If 315/51R21 is unavailable, the closest same-diameter substitutes on the same rim are 305/53R21 and 325/49R21. 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 315/51R21 you can upsize to 325/46R22 (plus-one) to fit a larger wheel without changing the speedometer reading, or downsize to 305/57R20 (minus-one) for a softer ride or winter setup. Both stay inside the Âą3% diameter tolerance that ABS and TPMS systems expect.
Vehicle compatibility
0 vehicles in our database run the 315/51R21 tire size from the factory. Aftermarket fitment depends on rim width, offset, and clearance â match these specs to your wheel before purchasing tires.
Vehicles Using 315/51R21
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