Tread or thread?
 

During walk around what is supposed to be checked on tires? The treads are good or thread is not visible?
Tread or thread?

Hi gunamani,

Before your post gets flamed and probably sent to JB....welcome to Pprune!

The correct word is "Tread". "Thread" is either a piece of string or the start of a post on a website.
So....on your pre-flight walk around, you are checking the tire TREADS. :ok:


So, again...welcome to Pprune...fly safe!

Actually the 'Thread' is what is visible when the rubber is worn away to the tire's carcass. This is the usually the absolute limit and the tire must then be replaced. Check your AOM or company ops manuals though, it might specify a minimum tread depth. Most decent western airlines will change the tires well before this point.

But we dont all work for these kinds of airlines. :E

G'day gunamani,


Welcome to PPRRuNe! :ok:

A bit of both I reckon, the tyre wear limits should be in the ops manual for the aircraft type.

There is quite a range of allowable wear, cuts and other damage allowed on the type I fly, sometimes with a limit on the number of landings allowed or the requirement to be inspected after each landing.

For the other two respondents, I think you need to re-read gunamani's post again, carefully. :p

Regards,
BH.

The 'Threads' or reinforcing cords are allowable on certain a/c or tyre depending on the manufacturer this is specified in th AMM. The tyres carcus plys these days are normally made of steel. So if you see them then it's normally time toi change the wheel assy.

Cords and ply ratings are based on the original construction when the plys were made from cotton/nylon.

Goodyear Tire Resource

Should answer the question.

Every type I've flown, according to the manufacturers own manuals, has a wear limit on the tires until the fabric or plys of the tire are exposed. The fabric (or often steel) is also known in non technical terms as 'the threads'.

:ok:

Despite what your operator or has published, the thread is the wear indicator for the tire installed by the manufacturer for the purpose of indicating a tire is approaching wear limits. Retreads often end up installing a new thread layer so multiple are possible. The further you wear a tire beyond the indicator the more expensive a retread gets.

Is it safe to operate a tire with thread showing? yes..

Is it legal to operate with no groove or thread showing? Up to the aircraft manufacturer and your operator.

I can defer a tire with exposed thread until it gets to the 1st cord or earliest available ground time on multiple aircraft types with my operator.

Something worth remembering is that running with a tire with no tread remaining, whilst structurally sound, will have very poor wet runway performance. So a bogey full of worn tires, or on smaller aircraft with single wheel gear, aqua planing becomes more likely or even inevitable. With modern anti-skid systems, retardation whilst aquaplaning might as well be nil!!

We change out at 1-2mm overall if possible.