175/45R21 Tire Size Specifications
This tire size 175/45R21 fits 0 vehicles in our database.
Everything to know about the 175/45R21 tire size
Size geometry
A 175/45R21 tire has a 175mm section width and a 45% aspect ratio, mounted on a 21-inch rim. Sidewall height works out to 78.8mm (3.10") and overall outside diameter is 690.9mm (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 175/45R21 is unavailable, the closest same-diameter substitutes on the same rim are 165/48R21 and 185/43R21. 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 175/45R21 you can upsize to 185/36R22 (plus-one) to fit a larger wheel without changing the speedometer reading, or downsize to 165/55R20 (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 175/45R21 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 175/45R21
tire_size.no_vehicles_found