C1 Tread Code
C
Service category — which machineCompactor
Rollers and compactors, where the tyre is part of how the ground gets compressed.
1
Tread type and depthSmooth Tread
No tread pattern at all. The whole depth is solid rubber, so there is the most possible material against cutting and the least possible grip.
ETRTO
The same code under the other standardSmooth Tread
ETRTO Standards Manual 2026 lists C-1 as a smooth 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.