Speed Limits - Tyres

There has been a great deal of kneejerk misinformation regarding the supply and use of J Rated tyres.

Much incorrect information has been circulated.

As a result of the Unions enquires, the following correspondence is attached:

From FENZ to NZTA

As discussed last week, Fire and Emergency are currently using tyres with a J speed category on some of our fire appliances (fire engines) in Auckland and Wellington. We have fitted these tyres at the separate recommendation of two of our tyre suppliers that these tyres are best suited to the type of usage and conditions the tyres experience when used on these particular trucks. This is typically relatively heavy cornering when responding to emergencies, where the tyre companies have recommended a tyre with a strong/stiff tyre wall to help keep the full tread on the tyre firmly on the road under heavy cornering. The tyres they have recommended have a J speed category, which equates to a speed of 100km/h at the maximum load specified by the tyre load index. Fire and Emergency policy is that some of our appliances can travel at a maximum speed of 105km/h.

In both cases the tyre load index supports a maximum load per tyre greater than the actual load on the appliances’ tyres, and greater than the NZ legal axle weight limits. Therefore the tyres are not loaded to their maximum, and both E/ECE324-E/ECE/TRANS/505/Rev.1/Add.53 and the relevant standard of the Japan Automobile Tire Manufacturers’ Association (attached) specify the relationship between the maximum speed the tyre can support and the maximum load on the tyre for J speed category tyres. Both of these standards say that if a J category tyre is operated at 105km/h then the maximum load is reduced by 2%, and at 110km/h the maximum load is reduced by 4%.

For example, our understanding is that we are able to safely operate tyres with a J speed rating and a load index of 150/145 at 110km/h for the following reasons:

The attached ECE document Annex 8 shows how the maximum load per tyre is reduced as the speed increases above the tyre speed rating. It shows that to operate a J speed rated tyre at 110km/h the maximum load on the tyre is then reduced by 4%.

Applying a 4% reduction to the front axle results in a maximum front axle load of (2*3350)*0.96 = 6432kg which is well over the legal front axle limit (6000kg) and well over the weight on the front axle on our appliances. A 4% reduction on the rear axle results in a maximum rear axle load of (4*2900)*0.96 = 11,136kg which is well over the legal rear axle limit (8200kg) and well over the weight on the rear axle on our appliances.

We have the attached letters from the relevant tyre manufacturer’s to support this understanding, and we also have an email from another tyre supplier (Bridgestone) confirming that “technically speaking” our understanding is correct.

The second issue is whether there is a legal compliance issue, even if there is not a safety issue.

Our understanding is as follows:

2.2(3) Land Transport Rule: Tyres and Wheels 2001 (“Tyre and Wheels regulations”) provides: “The speed category of a tyre fitted to a motor vehicle must be compatible with the maximum legal speed limit for the vehicle”

The J rated tyre used on our vehicles is rated to a maximum speed of 100km/h at the maximum load specified by the tyre load index (noting as above, we are in receipt of correspondence form Michelin and Giti confirming that within certain weight limit, FENZ’s J rated tyres may be used above the 100kph J rated tyre limit).

The legal speed limit for a heavy vehicle is 90kph – i.e. within the maximum speed limit for the J rated tyre therefore we are not in breach of this rule.

s5(1) Land Transport (Road User) Rule 2004 provides:

(3)
A driver who drives at a speed exceeding the applicable speed limit is not in breach of subclause (1) if the driver proves that, at the time the vehicle was being driven,—
(a)
the vehicle was being used by an enforcement officer engaged on urgent duty and compliance with the speed limit would be likely to prevent the execution of the officer’s duty; or
(b)
the vehicle was an emergency vehicle being used in an emergency and was operating a red beacon or a siren, or both; or

For emergency service vehicles such as our fire appliances being used in an emergency, the legislation provides that there is a speed limit, but no breach for exceeding it. The speed limit for our appliances in this situation is theoretically 90kph (as a heavy vehicle), but there is a statutory exemption for that vehicle which provides that the vehicle may in specified circumstances exceed that limit. In exceeding 100kph (the maximum speed at the maximum load specified by the tyre load index) there is no specific breach to the Tyres and Wheels regulations as the tyres are compatible with the maximum speed limit for the vehicle. The vehicle may in certain circumstances travel at a speed above 100kph, but the legislation is drafted such that the speed limit remains 90 km/h and is still applicable to our fire appliances. As a consequence, the speed limit of 90 kph remains applicable to any other regulation related to speed – including the regulations providing for maximum tyre ratings.

In addition, the Tyre and Wheels regulations are drafted to provide flexibility around the use of tyre ratings. Rule 2.2(6) provides “In assessing whether 2.2(1) to 2.2(5) are complied with, a person specified in section 4 may take into account evidence that the complete assembly of tyre, wheel, hub and axle is within the vehicle manufacturer’s operating limits”. Arguably this provides flexibility around the interpretation of 2.2(3) – which has been done and which is provided for with correspondence from Giti and Michelin – both of whom have confirmed that the vehicles can in certain circumstances be used up to 110kph.

Could you please provide an NZTA position on:

The safety of our use of the specified J speed category tyres in the circumstances described in this email given the supporting information we have provided, and
Whether there is a legal compliance issue our use of the specified J speed category tyres in the circumstances described in this email given the supporting information we have provided.

I would be happy to provide any more information that you may require and to discuss any preliminary view you may have before you settle on a final position.

A) Please see attached Fax  
B) Please see attached Michelin letter.

Reply from NZTA – Principal Engineer Vehicle Standards:

I apologise for the delay in getting back to you, I have talked this through with a few people now and as I think I mentioned previously the Transport Agency do not ‘endorse’ or ‘approve’ anything.

We would however fully support any advice provided by the manufacturer of any given components service limits. Therefore I don’t see an issue with the use of the tyres under the conditions you described providing you hold the supporting evidence from the manufacturer.

I’m sorry that I am unable to be any more specific than that.

Email from the Fire Service to the Union:

Peter Nicolle asked us to provide the NZPFU with some information regarding tyres with J speed ratings following the concerns raised by the Auckland Local.

The tyres with the J speed rating (maximum speed 100kph) being questioned by the Auckland Local (GT now branded GiTi) were trialled (beginning in 2014) at the recommendation of our tyre supplier with the aim of providing a tyre better suited to our operational conditions. The Auckland Local were notified of the trial at the time, but this notice didn’t bring particular attention to the 100kph rating of the J tyre. The aim of the trial was to assess whether the GT tyre would perform better on our appliances than the tyre generally used at the time, which were showing signs of sub-optimal performance on some appliances. While the GT tyre was more expensive than the previous tyres, the results of the trial were positive and the tyre supplier concluded that they were a superior tyre for our type of use. As a result, we proceeded to install them on other appliances. Currently there are 12 appliances with these tyres fitted in Auckland.

Independently, at the recommendation of one of our tyre suppliers in Region 3, we have also undertaken a long term test with a similar type of Michelin tyre in Wellington and also come to the same conclusion as in Auckland, which has also resulted in J rated tyres being fitted to 21 Region 3 appliances to date.

We are not wedded to the GiTi tyres, but we have no reason to believe that the GiTi tyres are unsafe and they were put on the appliances with the aim of achieving better tyre performance. Tyres have a speed rating and a load index which specifies the maximum load (weight) that the tyre can support. The J speed rating means that the tyre is rated at a maximum speed of 100kph at the tyre maximum load specified by the load index. With commercial tyres there is a relationship between the maximum speed of the tyre and the weight that the tyre can support. More weight can be carried if the maximum speed is reduced, and less weight than the load index specified can be carried if the maximum speed is increased.

Our understanding drawn from the attached document (particularly Annex 8) is that the J speed rated tyres can be operated at 110kph as long as the maximum allowable front axle loading is reduced by 4%, which equates to 6432kg on the front axle which is well over the legal front axle limit (6000kg) and well over the actual weight on the front axle on our appliances, and 11,136kg on the rear axle which is well over the legal rear axle limit (8200kg) and well over the actual weight on the rear axle on our appliances. GiTi have confirmed that the maximum allowable tyre loading needs to be reduced to operate at 110kph. They have recommended 6090kg max on the front axle and 10,554kg on the rear axle (letter attached). While these figures differ to those in the attached document, the outcome is the same i.e. that the tyres can still support the full legal load limit on each axle and therefore can support the weights of our appliances. Therefore our view continues to be that the tyres are safe.

We have also asked the Michelin tyre supplier to confirm our understanding with regard to their tyres and have recently received the attached letter. This also confirms that their tyres can support operation at 110kph.

The current situation is that two separate tyre suppliers have independently concluded that this type of tyre is better suited to the way we use our appliances and the way they perform, based on their observations of the effect on the tyres of our usage (including our emergency response driving, cornering and speed).

We are more than willing to discuss this with the NZPFU including whether we should continue with these tyres which have been recommended by our tyre suppliers, or revert to the previous type of tyres. We are also open to reviewing any ongoing actions should any new information come to light.

So the NZ Transport Agency doesn’t see an issue with the use of J Rated tyres under the conditions as outlined to them.

Job Sizing

As per the Terms of Settlement of the Collective Agreement, the Union has already commenced discussion with the Employer regarding the various matters covered in the TOR including:

  • Recognition of the effect of Medical Response.
  • Examination of the Peer Group currently used.
  • Changes resulting or expected to result from the Target Operating Model for all members including Operational, Fire Safety and Trainers.

The earlier the exercise is commenced, the earlier members will see the beneficial outcomes.

Recruiting and Retaining Firefighters in Auckland

Again acting on the need to commence discussion as soon as possible the President and Secretary along with Auckland Local Officials Martin Campbell, James Hall and Boyd Raines met with the Director of P & C – Brendan Nally and his Senior Staff to start work to establish Terms of Reference for a Project to look at what can be done on a wide front to assist with Auckland staffing difficulties.

The Employer was open in acknowledging the problem and accepting that they have a responsibility to act to fix the problem.

Further discussion on TOR, membership and Project Operation will occur later this week.

This is a very significant Project for Auckland members and the attendance and contribution of the three Auckland Officials was very significant in the making of progress – all credit to them.

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