SH4 Tread Code
SH
Service category — which machineSubterranean haulage
Underground haulage, where the tyre works in a confined space and heat has nowhere to go.
4
Tread type and depthDeep Tread
Around half again the depth of a regular tread. More rubber against cutting, and more heat.
ETRTO
The same code under the other standardDeep Tread
ETRTO Standards Manual 2026 lists SH-4 as a deep tread. Using these codes at all is left to the individual tyre maker, so a tyre may be marked to ETRTO, to TRA, or to neither.
TKPH
What the code does not tell youNothing about load, or heat
A tread code says which machine and how much rubber. What the tyre can carry comes from its star rating, and whether it survives the haul comes from TKPH — the load and speed it can work at without overheating. A deep tread on a long, fast cycle is a tyre being cooked.
Standardised by ETRTO or TRA.