The UK Professional Drivers Discussion forum
21 posts • Page 1 of 1
This was on the news today....
Drivers ignorant of safety basics
Road safety group says tyre tread levels should be increased
Roadside rescue company Green Flag has joined Brake in the campaign to increase the depth of tread required by cars and vans to 3mm.
Stopping distances at 50mph
Tread of 8mm: 25.9metres
Tread of 3mm: 31.7metres
Tread of 1.6mm: 39.5metres
(source: Brake/Green Flag)
The minimum legal lorry tyre tread depth is only 1mm - should that be increased? - what to?
I imagine that MOST decent owners would not let them get that low
That is correct
How much difference does tread make on a lorry?
On a dry road the main concern is getting the most rubber in contact with the ground so tread depth makes no difference until the tyre is completely bald, then grip is actually increased a tiny bit.
On a wet road it's more complex because you need to avoid aquaplaning, that's what the tread is for. Cars, especially modern ones with wide tyres, will easily aquaplane due to the low ground pressure and high speeds. By contrast a bicycle doesn't need any tread as the high ground pressure (80-100psi) and low speed isn't enough to lift the tyre off the ground. (OK, it's not impossible, Schwalbe calculated that a slick would aquaplane at around 200Kph).
My guess is that the similar high ground pressure of a lorry tyre, combined with the restricted speed makes tread depth less important than for a car, although still more important than for a bike.
Anyone able to do the science bit?
I like mopeds - only need visible tread!
I think they should leave the minimum where it is. I'd personally change my tyres at 2mm and buy some half-decent ones, not teflon specials.
A tyre is only useful when it's in contact with the road. Should be more of a test at MOT time to dampers on vehicles. I never seen a MOT tester bounce a corner. They just seem to visually inspect them.
The tread is there as stated for wet roads as each groove or sipe acts as a pump to remove the water from under it.
Slicks used on a race track are not just bald tyres, they are carefully engineered to heat up quickly without overheating or delaminating under severe conditions by using different compounds or materials.
As Rog already said, Trucks and Motorcycle tyres (1mm) have a lower legal tread depth than cars (1.6mm)
Agree, tread depth is effectively irrelevant in the dry.
Tread depth, pattern, material (eg silica content), and costruction all affect wet weather performance.
Given the amount of water that collects in the tramlines on some roads the road used by trucks is often "wetter" than it would otherwise be
sometimes tread depth is also irrelavant in the wet too.
three axle tractors love to go straight on irrespective of where the drivers wants it to go
i hated going to weddings. all the grandma,s would poke me and say "your next".
they stopped doing that when i started doing it to them at funerals.
tread depths...eh. Dont really affect me our garage hot snot at keeping our tyres legal. Only becomes a problems when it is flat at the bottom and 3 in the morning!!!
Man starts courting a beautiful chinese lady. Finally they get it together in the sack when she turns to him and asks what he would like...
A 69 he replies...
Bugger off she says I'm not bloody cooking at this time of the night!!
i am starting my own tyre supply company for lgv and cars i think the tread depth should be minimmum 5 mm acros full width of tyre with no cut anywhere on the tyre .No really i think the laws on tyrers is just fine as it is.i think they are trying to drum up more trade .i do not see anywhere near the amount of blown tyrer s on theroads as there used to be. if brake want to do more on safety get the hours cut to something sensible like the train drivers but with no loss of pay
One of the motoring programmes (Fifth Gear IIRC) did a test where they compared the stopping distance of a car with 1.6 mm tread against one with 3 mm tread, and the difference was quite considerable.
Of course, it would be interesting to know what they did to confirm that all the other conditions were identical (e.g. condition of the brakes, etc...)
I've aquaplaned on my bike - mountain bike tyres (about 5 cm wide), tyre pressure about 45-50 psi, and I hit a deep (approx 3-5 cm) puddle stretching across the whole width of the road at about 40 mph. Fortunately, I only wanted to go in a straight line, and the puddle was only about 5 metres long.
I think that is because remoulds are now used less than they were.
Also speed limiters play a big part in the reduced tyre blow outs.
I remember being told that the downward force on the front of a trailer, which equals more weight on the drive axle of the unit, is a couple of ton per mph after 60 mph.
Now just look where abouts you see the blown tyre carcasses nowadays and I reckon it's about right!
Tyre construction has changed dramatically over the last few years and now people do take a bit of notice about running correct pressures.
Tyres run cooler, they are constructed with more durable materials. Just look in a scrapyard and see if you can find a D20 and look at the difference.
It doesnt stop the trail of rubber and bent mudwings if you run down to somewhere hot with 16'' low profiles and have a habit of clipping kerbs
Highway code stopping distance for 50mph is 53metres anyway, so even with 1.6mm you're still well under the supposed stopping distance they expect, and have thus based all the speed limits, 2 second rules and so on around, don't see the problem personally. Make everyone drive everywhere at 10kph, or not drive at all, walk instead, mind you that's dangerous, what with kerbs, walls, lamposts and other things to hit.
Any vehicle with a gross vehicle weight (GVW) or gross train weight (GTW) over 3500kgs or a motorcycle above 50cc must, either:
The grooves of the tread pattern must have a depth of a least 1 mm throughout a continuous band measuring at least three-quarters of the breadth of the tread and round the entire outer circumference of the tyre, OR
if the grooves of the original tread pattern of the tyre do not extend beyond three-quarters of the breadth of the tread (i.e. common with motorcycle tyres) any groove of the original pattern must have a minimum depth of at least 1 mm.
remoulds should have the same durabuility has new tyres
incorrect pressure is the major cause of overheating and blowouts
their was some stuff in T&D years ago about Bandylegs remoulds
are they still going ?
THE LAW over here inEurope is that the minimum tread depth is
1:6mm and this is for all of the TYRE-TREAD sorry bit i belive
you will also mfind that if stopped and checked any one
found with a tread depth which does not mit the MINIMUM
tread depth requirements will, get done,by the way FOR
Germany it is €250 and 3points on your licence for each
TYRE, and the owner of the vehicle gets done as well,
Maybe before they hit the law abiding and Conscientious with tighter legislation, they should do more checks on all vehicles for tyre wear, incorrect pressurs and faulty dampers.
And it's not only the dodgy bunch who drive their vehicles in such a state,
I've seen newish cars full of children on the school run with obviously underinflated tyres or on the motorway with the wheel hardly touching the ground due to faulty dampers.
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