12.5 inch wide tyres on 8 inch rims

[blkmav]

I know this subject has been discussed many times....

I've been told that an engineer will not pass 12.5 inch wide tyres on 8 inch rims. This is due to the 'tyre and rim association' manual stating a 12.5 needs a 8.5 rim. Hence can't engineer on a patrol as 8 inch is widest rim fitment.

Apparently the 2005 version of the 'tyre and rim association' manual has changed this and 12.5 are approved fitment on an 8 inch rim.

Does anybody have access to the 2005 'tyre and rim association' manual?

[hypo]

this is good news if its true

[ozy1]

when i spoke to my engineer this year, he would not allow the 12.5's on an 8" rim,

but he did say, to me, that he would do them if i bought them in on a 9" rim, which are expensive and hed over look the minor detail of the inch to wide...........

but i havnt bothered.

[bogged]

I know this subject has been discussed many times....

I've been told that an engineer will not pass 12.5 inch wide tyres on 8 inch rims. This is due to the 'tyre and rim association' manual stating a 12.5 needs a 8.5 rim. Hence can't engineer on a patrol as 8 inch is widest rim fitment.

Apparently the 2005 version of the 'tyre and rim association' manual has changed this and 12.5 are approved fitment on an 8 inch rim.

Does anybody have access to the 2005 'tyre and rim association' manual?

many others have had 12.5's engineered on 8's in the past.. I have for one.

[blkmav]

If you went to Kevin Williams he won't do 35x12.5 on an 8 inch rim anymore. He won't even do 33x12.5 on an 8 inch rim.

[hypo]

I know this subject has been discussed many times....

I've been told that an engineer will not pass 12.5 inch wide tyres on 8 inch rims. This is due to the 'tyre and rim association' manual stating a 12.5 needs a 8.5 rim. Hence can't engineer on a patrol as 8 inch is widest rim fitment.

Apparently the 2005 version of the 'tyre and rim association' manual has changed this and 12.5 are approved fitment on an 8 inch rim.

Does anybody have access to the 2005 'tyre and rim association' manual?

many others have had 12.5's engineered on 8's in the past.. I have for one.

engineering is one thing being legal is another

[bogged]

If you went to Kevin Williams he won't do 35x12.5 on an 8 inch rim anymore. He won't even do 33x12.5 on an 8 inch rim.

I've heard hes pretty much pulled the pin totally on engineering 4wds at all.

[-Nemesis-]

My engineer told me that 12.5" tyres can be engineered on 8" rinms IF there is supporting documents from that tyre manufacturer claiming it is suitable. Most tyre companies claim 8.5" minimum.

Mickey T's on most of there's recommend 8" as a minimum, I just showed him the spec sheet from MT showing Claws are ok on an 8" and he was fine....

[bogged]

My engineer told me that 12.5" tyres can be engineered on 8" rinms IF there is supporting documents from that tyre manufacturer claiming it is suitable. Most tyre companies claim 8.5" minimum.

Mickey T's on most of there's recommend 8" as a minimum, I just showed him the spec sheet from MT showing Claws are ok on an 8" and he was fine....

You need it on a company letterhead with the facts backing you up. KW used to pass BFG's without problems 12/5 on 8's but now not even those will be passed.

[Ryano]

Mickey T and Cooper both passed 33 and 35's on 8" rims years ago.

The Tyre and Rim Association of Australia 2005 edition states in Section B page 10.... B-10:
SIZE - APPROVED RIM CONTOURS
33x12.50R15 - 8J, 8.5J, 9J, 9.5J, 10J, 10.5J, 11J
35x12.50R15 - 8J, 8.5J, 9J, 9.5J, 10J, 10.5J, 11J

As a thought.... although this does state that it is ok to use on an 8" rim, if the tyre manufacture does not specify that an 8" rim can be used, then I can't see how this can overide the manufacturers approved rim widths.
I spent some time earlier last year contacting the overseas manufacturers on a few different brands for approval of their 33 and 35" tyres on 8 "rims.
In the words of one asian tyre manufacturer....

Dear Mr.Ryan,
Recording to our R&D's testing report of the sizes 33x12.50 R15 and 35x12.50 R15,
our standard is testing in 10" rims and the fitment for the both sizes is 8.5-11.
Because our testing performance basic on the safety,
so, our testing standard will focus on the speed and durable.
Also it will depends on what kind of the terrain,
we understand the Mickey Thompson Tires and Cooper Tires in the USA has approval on the 33 and 35 in 8"rims.
But we don't know what kind of the testing performance and terrain are they basic on.
If the rims is much more smaller as a 8",
it will affect the side wall change the shape easily.
Because our standard is maintain the safety structural,
so, our R&D will not suggest to use 8" rims on the both sizes.
Please do not be hesitate for any questions.

From my correspondence with a variety of manufacturers, I have the feeling that it costs too much money to do more testing on the tyres to get approved for an 8" rim, when they have only had one request for it from a guy in Australia.

Hope it helps,
Ryano

[Screwy]

mine had 15x7 inch rims on a 33x12.5 when i had engineers pass it a few months back....

screwy

[droopypete]

engineering is one thing being legal is another

What do you mean by this?
Peter.

[ozy1]

mine had 15x7 inch rims on a 33x12.5 when i had engineers pass it a few months back....

screwy

read your engineers report, it will state that you are engineered on standard tyres, which means, if you ever have to go to the RTA, you will be required to go on 31x10.5's, or whatever is on the place card, maybe even splittys

[droopypete]

I can't speak for screwy, but I had my zook engineered with 33" BFG's and that is the size on the report, he even gave me a new tyre placard stating the same.

The whole idea of going to the trouble and expence of an engineer is to have your car (or my car in this case) road legal.
Peter.