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 Post subject: Matador tyres
PostPosted: Mon May 07, 2012 4:23 pm 
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Joined: Mon May 07, 2012 4:18 pm
Posts: 20
Hi All. Can anyone tell me if it is possible to fit 1600X20 tyres to a Matador?

Regards
Bob


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 Post subject: Re: Matador tyres
PostPosted: Wed May 09, 2012 11:48 pm 
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Joined: Mon Jan 16, 2012 11:19 pm
Posts: 12
Bob,

With care it is.

Adjust steering stops (particulary the exhaust down pipe clearance).

If heavy loaded will require wheel arch repositioning (1 inch - as 16x20 not 14x20).

Regards


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 Post subject: Re: Matador tyres
PostPosted: Sat May 12, 2012 7:18 pm 
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Joined: Mon May 07, 2012 4:18 pm
Posts: 20
Hi Matmetal and thanks for that. as my Mat is a timber tractor there will be no problem with the rear wheel arch as there aint any! the exhaust runs out the back of the cab so no problem there either, so all I have to do is adjust the stops to prevent the front tyres hitting the wheel arches,

Bob


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 Post subject: Re: Matador tyres
PostPosted: Mon Jun 04, 2012 8:01 am 
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Joined: Thu May 31, 2012 4:03 pm
Posts: 36
But be careful, the larger the tyre, the lower the braking efficiency. Thats a big increase in diameter. Do you use it on or off road? If you use it on the road the following will apply.

Also the front tyres run close to the air hoses. Even on a Mat equipped with standard tyres they can make contact if not positioned correctly. Your secondary brake on the Mat is your parking brake. So with a failure in air thats all you have to stop with. Its VITAL your hoses miss the tyres.

I doubt if you will meet the legal minimum efficiency with 16.00's

As there is no centre diff you will need a matching set of tyres.

A common misconception is that as you are exempt MOT you are exempt construction and use. Not so. C&U still applies to your Timber Mat. If you have the misfortune to have a road accident with it, you will probably find Plod will turn up. They won't know what to do with it so will call VOSA out. They will know what to do and you will find it will be recovered under Police Powers and put over the brake rollers.

Sorry if this disappoints, but you would probably rather know some of this rather than not.

Paul.


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 Post subject: Re: Matador tyres
PostPosted: Tue Jun 05, 2012 12:21 am 
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Joined: Mon Jan 16, 2012 11:19 pm
Posts: 12
Paul is correct. C$U are a pain.

However modern rollers test each axle brake effort individually, the swept brake area per axle is the same as a Mk1 Militant (fitted as standard with 1600x20).

The important thing is that correct maintenance is carried out at 65 psi applied pressure.

The problem is really dont let the front hoses get damaged and drive what really is an underbraked, overweight (by modern standards) vehicle appropriately. (I doubt even brand new these wonderful vehicles would meet todays test standards.

Hope this helps.................


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 Post subject: Re: Matador tyres
PostPosted: Tue Jun 19, 2012 5:11 pm 
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Joined: Thu May 31, 2012 4:03 pm
Posts: 36
Good point Matmetal. However I must just add that swept area of the brake shoes / drums is not the end of the story, so you can't just assume it will brake ok.

Take a "Type 24" diaphragm brake chamber. Now its called a type 24 as it has 24 square inches of surface area. So 100psi x 24" = 2400 pounds of effort.

Now if we do the same sum on a type 20 diaphragm, well thats going to be 2000 pounds of effort. That 400 is a big chunk of effort.

OK lets see what difference the pressure on the gauge makes. The Matador cuts out at 90 PSI. Now 90 x 24" = 2160 pounds of effort. Hhm, 240 pounds down.

Now don't get me wrong Matmetal, I do not know what the size of the chambers are or what the Milly makes on the gauge - so it may be fine on your calculations.

As for "could one of these old machines pass the roller test in a HGV test station" question, well I can answer that. These Old Boys who designed our old machines knew a thing or two. I put my Old Mat through a voluntary brake test at Lancing Test Station a while back and it made the grade with ease. You only need 45% efficiency on something that old, not 50% as in a modern. Also the parking brake just has to work without a percentage given. Looking at the test card now I see that it made 93% on the foot brake and 29% on the parking brake. No its not modified & has the old Westinghouse system.


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 Post subject: Re: Matador tyres
PostPosted: Wed Jun 27, 2012 6:54 pm 
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Joined: Mon May 07, 2012 4:18 pm
Posts: 20
This is why I love these forums; they access such a wide range of information and advice.
Thank you to all of you who gave so much good advice regarding the fitting of larger tyres to my Mat.
This has allowed me to make an informed judgement, that is that the Mat was fitted with 1400x20 tyres and that it is best left that way!
Once again thanks to all of you who posted replies.

Best wishes

Bob


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