Difficult to find anything definitive, but the first regulation introduced in 1968 required 1mm of tread for all vehicles.
An EEC directive increased that to 1.6mm for cars and light vans in 1992 but not for HGV’s.
There was a lot of controversy about the car tyre increase due to the number of vehicles that would become illegal overnight (which I remember), and I bet the transport lobby had a lot to say about the “huge” cost of replacing all those truck tyres. I guess the transport guys had the clout to keep it at 1mm for them.
Remember that the tread is only useful in wet weather (if you watch F! you will know what I mean) so the depth is always going to be a compromise.
Lucky for me the sleigh is an exempt vehicle under the Roof Traffic Act 1851 as ammended in 1665.
Hi all those of us that are old enough to remember not having a tyre law at all lol and changing tyres when the inertube was showing, as Busby 06 quite rightly stated when the tyre law was first introduced it was 1mill across 3/4 of the width around the whole circumferance with no deep splits bulges or cord showing. Then we joined europe mmmmm and the change in tread depth for cars was signed up to. Now why motorbikes and trucks were not part of this agreement I can onlry say pass (this was also the time we sorry politicians agreed to come closer into line with europe on the VAT rate because we were bumbling along with our 8% oh happy days) as stated ealier we now bear no resemblace to the law in europe and car tyres are now across the centre 3/4. as a footnote I change my truck tyres at 2.5 mill 1 mill scares the ■■■ out of me.
Santa:
Difficult to find anything definitive, but the first regulation introduced in 1968 required 1mm of tread for all vehicles.
An EEC directive increased that to 1.6mm for cars and light vans in 1992 but not for HGV’s.
I wonder if that is because truck drivers do a daily tyre check and would notice if the tread got too low but the average car driver tends not to check such things so often
Santa:
Lucky for me the sleigh is an exempt vehicle under the Roof Traffic Act 1851 as ammended in 1665.
Ah, but the Roof Traffic Act 1851 amended 1665 states that sleigh runners have to comply with the Air Transport Regulations 1760 (amended 1761).
It states that only 27 million presents can be carried at one time, you are clearly
flouting those rules as it’s well known you carry significantly more than this.
H&S Executive also demands a santa must fit down a standard chimney.
Shall I place the first bet?
bubsy06:
tread is on a tyre for wet roads. I am asuming lorrys are heavier so they have less chance of aquaplaning so they can have a lower tread depth. light vehicles are more likely to aquaplane so have to have a minimum higher tread depth
what he said
Wheel Nut:
That argument may work but in that case why is the limit for 186mph motorcycles still only 1 millimetre?-
i would of said because a bike tyre isn’t flat on the road like a car / truck tyre. the profile of the bike tyre natually shifts the water to keep contact with the road. on a moped there is no actual limit, the thread pattern just has to be visable
bubsy06:
The only answer I can find is that cars minimum tread used to be 1mm but got changed to 1.6mm but they did not change motorbikes and lorrys up to 1.6mm.
And, therein, IIRC is where, I think, you will find the answer, Vehicles being used under an Operators Licence are subject to a regular inspection. Cars and light vans are not. They are (only required to be) inspected annually, once three years old. Prior to that, they will invariably be with a 1st owner who has a responsible attitude towards maintenance. Subsequent owners may be less diligent.
With regard to motor cycles. The tyres fitted to the vehicle tend to be more exposed as to a visual check of their condition and, if the manufacturers loaded more tread onto the casing to increase their life, then it would add to the ‘unsprung weight’ of the wheel and could be detrimental to the handling of the vehicle.
Didn’t we go through a period when the legal limit for cars and light vans was a minimum of 1mm, but the MOT minimum was 1.6mm?
Having now looked it up. The change occurred in the Road Vehicles (Construction and Use) (Amendment) (No. 4) Regulations 1990. Statutory Instrument 1990/1981.
If you look it up and read the preamble, then it might give you some insight behind the reasoning.
Krankee. I will look into the act further. I will also, time permitting make enquiries at the DSA training centre Cardington and anywhere else members and myself can think of.
The question asked, I feel is something that may be unfair by the council, as I had gone into reasonable depth on the subject as an overview.
Considering the presentation given, and taking the brief ten minutes allowed, It would seem harsh if everything came down this one point being the grey area it may now seem.
trucking482002:
Look on Yahoo answers,scroll down to why do cars and lorries have different tread depth requirements.
regards derek
I am with Chippy now. Even that doesnt really tell you the reason why.
I could accept the normal response from the woman stood behind me.
Because they do, right. or because it does.
But apart from the Rospa web suggesting it may have been a European directive and lorry tyres were neglected when legislation was changed because of pressure from the transport lobby. I dont know the answer
Maybe the definitive answer is found in Wikipedia.
A US penny can be used to check tire tread to see if it is down to 1/16 or 2/32 of an inch.
Take a penny and put Lincoln’s head into one of the grooves of the tire tread.
If part of his head is covered by the tread, you are driving with the legal amount of tread.
If you can see all of Lincoln’s head, it is time to replace the tire.
So it is Abraham Lincolns fault until the Europeans started to use a locally recognised coin and measured the depth in metric.
Hi folks so far no answer, the only one that came near was a Rospa bloke who reckons like Busby06 said . It’s something to do with water displacement.
That was his opinion, as for a legal definition he reckons Vosa may know or like Krankee has suggested look for the legislation and consultation documents as the change must have been debated in parliment to take affect.
The DSA by the way hadn’t a clue, nothing new there then. Not
not in the least.