305/30 R21 - Best allround tyres 2025 - market overview, tests, reviews

305/30 R21 doesn't belong to the most popular dimensions for allround 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 - 30 is height of the tyre, which is calculated as 30% of the tyre width (305mm), which means the sidewall height has 91.5 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 2250.64 mm, which is very similar to 235/55 R18(2248.44 mm), 235/50 R19(2254.41 mm), 265/30 R22(2255.04 mm), 295/35 R20(2244.67 mm), 265/35 R21(2258.49 mm), 205/75 R16(2242.78 mm), 235/60 R17(2242.47 mm).