305/35 R21 - Best summer tyres 2025 - market overview, tests, reviews

305/35 R21 doesn't belong to the most popular dimensions for summer tyres - there are 1 tyre models available, which can be compared to 155/60 R15, 170/60 R17, 160/60 R14. Let's break down the sizing - 35 is height of the tyre, which is calculated as 35% of the tyre width (305mm), which means the sidewall height has 106.75 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 2346.46 mm, which is very similar to 265/45 R20(2345.2 mm), 265/50 R19(2348.65 mm), 315/30 R22(2349.28 mm), 265/40 R21(2341.74 mm), 245/70 R16(2354.31 mm), 265/35 R22(2338.29 mm), 295/40 R20(2337.34 mm). There are multiple speed indexes available for summer tyres in 305/35 R21: Y(300km/h). The same goes for weight indexes: 109.