Original Tire Size for a 114/115
(And 108/111/109... and others)

OE tire (or tyre) is 185 HR14 which is 185/80HR14 in today's sizes. You can use 195/75HR14 but not 195/70HR14 like what was fitted to the W123 series as they will make your speedo incorrect and degrade your fuel consumption.

If you're a lucky so and so and have 15" wheels you want 205/65-15.

John Greene, Richard Sexton