Whats the difference between AO, MO etc etc tyres, as far as i know it means audi only, merc only etc. This being due to different sidewall construction/rim protection for different manufacturers.

Now this is where the confusion seems to arise, if you have an audi a3 on "AO" tyres all's good. If its on normal not manufacturer specific then it's all good. But say you had the same audi a3 on "MO" tyres, would this then be an MOT failure as "not fitted in accordence with tyre sidewall instructions"

Any input?

 

As far as I'm aware the tyres are tested for condition and the size is the same on each axle. I don't think speed rating comes into it either as my MOT tester fitted tyres with a 150mph speed rating on my car yet it is capable of more.

Am interested to know what the manufacturer specific tyres are all about though as I have always wondered!

 

Mate when i fail cars on test for 'not fitted in accordence with tyre sidewall instructions' its normally due to directional fault not all this AO MO stuff, all the AO and MO means that they are made with 'approved' moulds like the AO are audi approved tyres etc, its a load of balls to be honest mate, hope that helps

 

An mot tester will never check things like speed ratings or specific manufacturers on the writing on the tyres. Only things they do check are

Any lumps in the side wall

Splits in the side wall where cords are visible

Tread wear on centre 3/4 of tyre ( above 1.6mm)

Matching size tyres on same axle. Must be same size, width and wall height

Directional tyres fitted correctly.

Punctures will be pass and advise unless in a dangerous place. eg sidewall or edge or tread.

Maybe more im not sure, someone will confirm! but if an mot tester ever fails for speed ratings then hes just a dick imo

 

Yeah speed rating isn't really the issue, i'm just on about the vehicle manufacturer identification on the sidewall.

However, having looked here - http://www.motuk.co.uk/manual_410.htm - "f. a tyre not fitted in compliance with the manufacturers sidewall instruction e.g. an asymmetric with a sidewall marked ‘outer’ fitted with the marking to the inner side of the wheel.

Note: Direction of rotation may be indicated by an arrow and/or words, but an arrow by itself should not be taken to indicate direction of rotation"

Could you then say a tyre marked MO on an audi is now "a tyre not fitted in compliance with the manufacturers sidewall instruction " thus a failure?

 

p.s. cheers mods for moving it to a forum no-one looks at, i thought general car discussions would be more suited since i'm after a general discussion aimed at mot testers/tyre fitters, as opposed to people wanting to know what size tyres go onto my 19" rims on me escort innit bruv!

 

No you carnt fail it for that mate in regards for the MO or AO, it is all about safety, if the direction is wrong etc the water wont be moved away correct etc like i said before so that will fail and (as an MOT TESTER) its not a fail on the MO or AO as its not an instruction or safety mate