325/40 R21 - Best winter tyres 2025 - market overview, tests, reviews

325/40 R21 doesn't belong to the most popular dimensions for winter tyres - there are 0 tyre models available, which can be compared to 155/60 R15, 170/60 R17, 160/60 R14. Let's break down the sizing - 40 is height of the tyre, which is calculated as 40% of the tyre width (325mm), which means the sidewall height has 130 mm. The wheel diameter is R21, which means it fits to a 21 inch/533.4mm diameter wheel. The total circumference of the tyre is 2492.54 mm, which is very similar to 285/50 R20(2491.28 mm), 275/70 R16(2486.26 mm), 285/45 R21(2481.54 mm), 275/65 R17(2479.66 mm), 255/55 R20(2477.15 mm), 285/60 R18(2510.76 mm), 285/40 R22(2471.81 mm).