How much tread is effective ?

[Tentman]

Gidday guys

How much tread does a MT tyre need to be effective 3mm ?? 6 mm??

To put it another way, when you're looking at secondhand tyres for offroading how much is 50% worn ??

To qualify it a bit I'm after tyres for crawling up Canterbury riverbeds and the tracks in the river headwaters.

Thanks

[muddy]

New tyres typically around 15mm. WOF requires 1.5mm but less tham 5mm and they're pretty much buggered for offorad work. So they can be advertised as "half worn" at around 7-8mm, but effectively not much life left at that. In my mind half the value is gone in the first 3-4mm - so you should pay less than half new price if there's less than 10mm...

[albundy]

I have always said, once half worn, they're stuffed.

[mudlva]

20% worn 80% shot

[juz]

Agree with Al, if you flick them off early enough you can still get good $$$$ for them too.

[drive it ...]

Agree with the 20% worn = 80% of the effective life but thats in mud / grass / bush / etc.
In canty riverbeds up country its mostly all gravel so AT's or worn MT's are fine.
Also one of the best times to head up country is mid winter when there's snow on the ground and the rivers are low, in which case you'll want chains or simex's anyway.

[Dr_PC]

Mud and crap the 1st quarter is the best half. Canterbury rivers use to do them in a mk 1 humber 80 on crossplys so 3 mm is still going to work for you

[catalystracing]

20% worn 80% shot

Totally agree, my truck used to go at most stuff ok until now with tread under 50%, now it struggles.
Now its the wallet that suffers

[4WDbits]

20% worn 80% shot

Totally agree, my truck used to go at most stuff ok until now with tread under 50%, now it struggles.
Now its the wallet that suffers

The sharp edges on new tread give a lot of grip, 1/4 worn with rounded edges not so much.