Tyre depths
39 replies
Bob2112 replied on 12/02/2018 21:49
Chris Ardis replied on 15/02/2018 12:33
Posted on 15/02/2018 12:33
The original legal depth of 1 mm. was set when most tyres were narrow 145 to 185 mm. tread width. The current 1.6 mm. limit was introduced as tyres got wider. Since then they have got wider still with 225 to 245 mm. being common widths. However tyres still only have 3 or 4 grooves to dispel water. It therefore makes sense to change at 3 mm. depth while there is still a sufficient channel for the water to be dispelled.
I am a retired Road Transport Engineer and on my fleets of buses & coaches we always re-grooved and renewed tyres at 4 mm. depth. We had tyres of 265, 295 & 315 mm. tread widths, again with only 4 main channels + 2 very narrow ones on the wider tyres. I would never let a heavy vehicle tyre get close to the legal limit and neither would any other self respecting Fleet Engineer.
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crusader replied on 27/04/2018 09:51
KeefySher replied on 27/04/2018 12:52
Posted on 27/04/2018 12:52
I go to the markers.
2.6 million + miles of driving cars all over the world.
I know a lickle bit about tyres from my work on tyre compound formulation, tyre cord development, delamination prevention and low temperature environments for tyres.
I also know of marketing around peoples lack of technical knowledge 
and the industry of elf and safe tea
Ive seen the police driver films where they drive at speed and knock cones, representing people, over instead of driving around them after locking the wheels up in a skid 
replied on 27/04/2018 19:52
Posted on 30/01/2018 19:14 by PhishingAbsolute min 3mm.
From ROSPA:
Stopping distances start to increase dramatically at tread depths of below 3mm. At the legal minimum tread depth of 1.6mm, the stopping distance is increased by 36.8% on the hot rolled asphalt and
44.6% on the smooth concrete.OR 5 years old regardless of how deep the tread is.
tigerfish replied on 27/04/2018 20:25
Posted on 27/04/2018 20:25
DD, The rubber compounds on F1 cars are very different from Road legal tyres. I agree with many of the foregoing and rarely allow my tyres to go much below 3mm's.
My car wears all 4 tyres at very much the same rate and when off the car the profile is such that you cannot tell the fronts from the rears, The drawback is that I always have to buy all four at the same time. They last about 35,000 miles per set. or every 4 years.
TF
EmilysDad replied on 27/04/2018 21:40
. Could it be that the bigger the surface area in contact with the road, the better the grip replied on 28/04/2018 07:44
Posted on 27/04/2018 20:25 by tigerfishDD, The rubber compounds on F1 cars are very different from Road legal tyres. I agree with many of the foregoing and rarely allow my tyres to go much below 3mm's.
My car wears all 4 tyres at very much the same rate and when off the car the profile is such that you cannot tell the fronts from the rears, The drawback is that I always have to buy all four at the same time. They last about 35,000 miles per set. or every 4 years.
TF
tigerfish replied on 28/04/2018 09:56
Posted on 28/04/2018 09:56
DD, Sorry I misunderstood your point. Total agreement with the above, and would also add one more point! Age!
My wife's car recently failed its MOT because of perished Tyres! The car is 8 years old now and has done16,000 miles, - only 1,200 since the last MOT. The tyres looked great hardly any tread ware visible but the garage found severe cracking on all 4 due to the sun and age.
4 new tyres later, she still wants to keep the car because it gives her independence!!
TF
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rjb