Hmmm

Well I guess there are different rules for other states but here are some information sheets for NSW.

http://www.rms.nsw.gov.au/roads/safety-rules/vehicle-standards/information-sheets-specifications.html

VSI 09 - Guidelines for alternative wheels and tyres

A small quote !

As a general rule, it is recommended you only fit wheels and tyres that are listed on the tyre placard or in the
owners handbook. These have been tested and proved for your car.
Sometimes the range of wheels listed by the manufacturer may appear to be limited. While it is recommended
that you only fit these wheels, the RTA does not oppose the fitting of wheels outside the range providing they are
safe for the vehicle.

Make of it what you will !! For some reason the car is OK but the high tech caravan has more constrained rules !!!

Jaahn

Jaahn,  yes WTF is what we said.  But the QLD DOT have told us that there can be no modifications done to trailers without a compliance plate.  Vehicles are covered by a number of different codes which allow for certain alterations to occur.  

Kimsay wrote:

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Jaahn,  yes WTF is what we said.  But the QLD DOT have told us that there can be no modifications done to trailers without a compliance plate.  Vehicles are covered by a number of different codes which allow for certain alterations to occur.  

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 I think you are paraphrasing what you were told and not getting things correct. They were possibly replying to a specific question asked by you. Read this page. It applies equally to all vehicles. There are modifications you can do on vans that do not not require recertification. For instance adding packing sections between the springs and chassis to get more clearance generally does not require recertification.. Your local motor registry should be able to supply you with a list of signatories or advise where you can get one.

Kimsay wrote:

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Hi all. We have recently purchased a van with 14 inch rims and want to change them to 15 inch rims.  This doesn't seem to be as simple as we first thought due to compliance issues.  Does anyone know the name of a mechanical engineer in the greater Brisbane region who would offer advice, certify this change and issue a 'blue plate'.  TIA. 

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 Hi Kimsay,

Perhaps you should detail what you wish to achieve. What is the reason for the change. To increase the overall diameter? put on the same wheels as your tug ? fit better tires ? bargain set of wheels and tires or ??

What is the weight of the van and the axles, tires capacity ?

Jaahn 

Middo, that would be Caboolture Caravan Repairs. They do a lot of upgrades but do not do the certifying (conflict of interest potential problems.) They use an independent assessor to certify their work . Give them a ring and ask who the certifying engineer they use is.

Jamjar wrote:

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I too wonder why the change?

1..  While I was in Sydney, at the beginning of the month, I discovered that my van's tyres where showing perish signs.

2..  As I was having a front of car lift problem I asked the chap at Bridgestone if changing the van's 14" rims to match the 16" on the car would help. I was thinking that the van was too low for the car.

3..  He looked up the two sizes in a book, showing me that the height difference was almost the same.

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1..  How old are the tyres. If they are perishing then they could be time expired (over 7 years old.)

2..  If you are having too much lift at the front end you have more problems than the "van was too low for the car." It sounds like you have a van with a high ball weight and you are not using WDH (weight distribution hitch.) Most WDH for the heavier vans come with an adjustable height hitch, this will allow you to lower your ball height and thus level your van. The WDH will also replace the weight back on the front wheels that you lost when you hitched up.

3..  Sounds like the tyres on the tug are very low profile tyres.

Maybe you should start another thread of your own to discuss this. When you do give us the full details of your rig. Amongst the details we require the ATM of the van (you find it on the compliance plate) and the measured ball weight.

As an aside, most tyre companies or suspension specialists know little about the levelling and dynamics of caravans. You need to approach one of the better caravan repairers for this sort of info. Caravan salesmen don't seem to know much either, they just have the gift of the gab to sell vans.