Upon return from 2018 trip as referred to earlier I immediately started the 'replace wheels and tyres' goal, knowing it would be a bumpy road, pardon the pun.
I offer the following to assist others who may be considering this change.
As a reminder I already have ATW 19.5 and Toyos which I'm not happy with. For those going from factory duals etc.,if you want to go singles then the options as I'm aware are ATW, Kym Bolton Truck SS, Alan's alloys, how far you go with compliancing is up to you and your risk profile. I live in Qld.
My journey...
1. Try to piggy back on a friends compliance for 37" Hankooks and Kym's 17" rims.
Result: Engineer wants to do the whole deal as if there had been no precendence set and I had no existing SSs from ATW
NHVR indicates via email that an engineer does have discretion to work from a sample vehicle. Our friend's vehicle is
essentially identical to ours. Engineer not swayed, says he doesn't know the condition of a used vehicle. I argue that
as a heavy vehicle it has had a recent COI and our odometer reading is 70k, which is a lot less than many vehicles who
roll in ,do some paperwork and throw on a set of wheels and tyres a drive away, those vehicles being later models that
have had compliance given for a representative sample. Older models are not currently covered.
2. Conversation with Kym's Truck Super Singles representative
Result: They discuss with an engineer and while not 100% , lean toward needing full testing if changing the rolling diameter. Since
Toyos come in at very close to 35" then a change to 37's is more problematic. However, they are now offering a Patriot
tyre in 35" with a 125Q load and speed rating which suits our 5500kg GVM. Can I just put these on considering they match
current approved ATWs in rolling diameter? ....hmmmm, so I'm given the name of an AVE ( Approved Vehicle Examiner)
in Ipswich. He says all good providing they are approved load and speed rated rims and tyres.
So, good to go...weeeell perhaps. See, ATW gave me a certificate in 2014 for the wheel and tyre change, a TA.033 form which states very specifically that the mods apply to their specific tyre and wheel package, They do the usual blue mod plates now but had this option back then. So, it is this grey area that is concerning me in a bureaucratic sense, not from a safety point of view.
3.Let's talk to some AVEs- Approved Vehicle Examiners- I ask...Can you just put a mod plate on to give certainty under the NHVR modification codes?
Result: "Yep, no worries, send me the ATW certification and we'll meet somewhere and put one on."
Next day: " Ummm, spoke with my boss and be says it's a bit of a grey area and to maybe not do that, sorry."
I research the NHVR codes and find the E3 code applies to axle,steering,wheels and tyre changes and that it is well
within the scope of an average AVE to certify what I want to do. I even download the tick sheet they use for the task,
and it looks straightforward to me considering I already have ATW second stage manufacturing approval.
The E3 code applies, oddly enough but not surprisingly, to the front only. So, I search for the code for the rear. I find the
D3 code applies to the axle diff whatever, but no reference to tyres and wheel changes. There is NO CODE for this!!!????
Turns out the rear wheels and tyres as per D3 code is in draft form. What went on prior to this for rear certification I have
no idea. Faaaark!
4. Based on the above I resolve to contact NHVR one last time. This takes over a week to get a response that basically reflects the
above paragraph, but does affirm that an AVE is capable of certifying wheel and tyre changes.
NHVR summary ...
a) 3 areas - Minor self assessable mods/ NHVR approved/ AVE approvable - I am concerned with the last category
b)Section 86- VSB6 ( Vehicle Standards Bulletin 6) - This is the primary standard used by AVEs to approve heavy vehicle mods.
c) If you search for VSB6 you will find the mod codes for different parts of heavy vehicles that can be approved by AVEs.
d) Codes E3 and D3 will be found in the VSB6
5. Let's talk to some more AVEs- like Dr shopping but for AVEs
Result: An AVE from Nambour ,with long experience, reinforces that as long as the basics of tyre diameter, offset and track changes fit within the specified allowances then it's a straight swap with load and speed rating proviso. He is also frustrated
by the lack of clarity from NHVR.
I'm reasonably satisfied that sticking to 35's with appropriate load and speed ratings and adhering to offset , track and tyre width parameters that I will be covering the safety related aspects of wheel and tyre modifications. The specific nature of the ATW certification is likely due to the desire to safeguard the development costs and certification of the package.
Note that Truck Super Singles has the Patriot 35s and 37s. They also offer the Gladiator 37, but my research has shown that Gladiator 35s are quite widely available in a 126Q rating. Availability and choice in the 35s is still more of an issue than 37s.
