345/30 R21 - Best allround tyres 2025 - market overview, tests, reviews

345/30 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 (345mm), which means the sidewall height has 103.5 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 2326.04 mm, which is very similar to 295/35 R21(2324.46 mm), 235/55 R19(2328.23 mm), 235/60 R18(2322.27 mm), 285/45 R19(2321.95 mm), 255/70 R15(2318.5 mm), 255/65 R16(2318.18 mm), 255/60 R17(2317.87 mm).