Tyres

[20Legend]

Hows many landing like this (http://www.airliners.net/open.file/1233928/M/) can tyres take before needing to be replaced?

Is there like an car MOT thread depth test?

[theamrad]

Can't give you any info myself - cause I don't change them :}
But you can try this link from Goodyear:http://www.goodyearaviation.com/boeing_b747.pdf
and if you want to know everything else about aircaft tyres:http://www.goodyearaviation.com/img/pdf/db_airdatabook.pdf and http://www.goodyearaviation.com/tirecare.html

[mitzy69]

tyres on landing about a 100. they smoke like this every landing.
depth of tread on tyre covered in CAA AWN 5, I think, and in maintenance manual. can have a bauld patch but tyre should have tread on remaining 75%.

[MD11Engineer]

It's a little bit more complicated than this.
Maintenance manual 32-45-00 Wheels and tyres, inspection will give you the exact limts.
Generally, since most western airlines re-thread their tyres, a tyre is worn to limits (WTL) if the thread reinforcement layers (about a millimeter or so below groove depth) are reached. Latest when the second one has been worn through the wheel has to be replaced to still be able to re-thread the tyre.
The tyre is generally scrap and out of limits if there are cuts reaching the carcasse plies (those which really carry the loads). The same applies to wear. Flat spots (really flat, not just WTL in some spot) can happen if either a brake locks or the anti-skid system is not working properly. Usually in this case the tyre is out of round and has to go.
Any damage to the sidewalls makes it U/S.
Cracks in the grooves are a no go if the thread reinforcement layers are visible.
This is by far not a complete list and in any case consult the respective AMM.
BTW, most Russian airlines do not re-thread their tyres but use them until they are definitely scrap. Due to this the wheels on Russian planes often look terrible.

Rgds,
Jan