135/80 R13 doesn't belong to the most popular dimensions for tyres - there are tyre models available, which can be compared to
325/30 R21,
155/60 R15,
155/65 R13. Let's break down the sizing - 80 is height of the tyre, which is calculated as 80% of the tyre width (135mm), which means the sidewall height has 108 mm. The wheel diameter is R13, which means it fits to a 13 inch/330.2mm diameter wheel. The total circumference of the tyre is mm, which is very similar to 195/40 R17
(1846.63 mm), 255/70 R18
(2557.88 mm), 195/60 R14
(1852.28 mm), 265/35 R21
(2258.49 mm), 195/70 R16
(2134.4 mm), 265/45 R21
(2425 mm), 205/45 R17
(1936.16 mm).
