What does speed rating H mean?

The letter that broke the alphabet

Read the speed symbol table from the top and it behaves: Q at 160 km/h, R at 170, S at 180, T at 190, U at 200 — ten more kilometres per hour for each step down the alphabet. Then, instead of the V you would expect, comes H at 210, and only after that does V appear at 240. H is not a misprint and not a manufacturer's quirk. It is older than the rest of the series, dating from a time when it was the high-speed marking rather than one rung of a scale, and when the graded scale was built around it the letter kept its speed instead of taking a new position.

What the rating is a statement about

210 km/h is a laboratory result, not a licence and not a promise about a particular road. The symbol records that the tire completed a standardised test at that speed on a machine, at a specified load and inflation, on a new casing. It says nothing about a tire with a nail in it, a tire at half its rated pressure, or a tire six summers old.

Where you actually meet an H

It is the usual marking on sport sedans and coupes, which is a narrower band than most people assume: touring tires for the same cars are frequently T or V instead, and winter tires for them are often two rungs lower, because a winter compound is built to work at temperatures where an H-rated summer casing is not.

Reading it in context

The symbol never appears alone. It follows the load index in the service description printed after the size — the tool below can be loaded with a full H-rated description to see both halves decoded at once, and the speed rating table lays out the whole series with the ordering anomaly visible in one column.