Daveg
NT & VTS Council member
I believe I am perfect, but others may differ in opinion?
Posts: 1,549
|
Post by Daveg on May 6, 2012 16:02:55 GMT
Got a couple of pictures of some tyres, please advise what you would do at MOT Time Dave Attachments:
|
|
Daveg
NT & VTS Council member
I believe I am perfect, but others may differ in opinion?
Posts: 1,549
|
Post by Daveg on May 6, 2012 16:04:53 GMT
Got a comparison same make and specifications Attachments:
|
|
prb5244
Nominated Tester
Posts: 124
|
Post by prb5244 on May 6, 2012 19:10:28 GMT
looks ok daveg looks more than 1.6 deepest cut centre 3/4
|
|
Daveg
NT & VTS Council member
I believe I am perfect, but others may differ in opinion?
Posts: 1,549
|
Post by Daveg on May 6, 2012 19:27:10 GMT
Got a couple of pictures of some tyres, please advise what you would do at MOT Time Dave With reference to the centre of this tyre and comparing it to the other tyre, the same make and specifications, and this first tyre devoid in the centre is NOT from new in its vulcanising process having grooves CUT > 1.6mm. Should it pass or fail by comparisons? Dave
|
|
|
Post by drivewasher on May 6, 2012 20:02:13 GMT
Both pics are the same make/type of tyre. The top pic has very little centre circumferencial (new word I think) tread left but as it's manufactured/designrd to wear out before the main full depth tread containing the TWI's then as long as any other full depth tread remaining in the centre 3/4's is not less than 1.6mm then it's a pass.
The bottom pic is the same tyre but not done as many miles/worn down as much as top pic.
I find problems arise from determining if the tread, particulary on the edges inside the centre 3/4's area doesnt meet the main tread if the tyre's getting worn as you can't see a "step"
Also it's not easy to judge from 2d pics! But I think this is where your coming from is it Dave?
|
|
|
Post by drivewasher on May 6, 2012 20:04:59 GMT
Oh when it's enlarged I can see that is the case
|
|
alex
Nominated Tester
Posts: 305
|
Post by alex on May 6, 2012 20:56:00 GMT
I would pass and advise on the top pic centre tread doesn't appear to be cut as deep as other part of tread,where I work we have a certain brand of tyre and when brand new that centre band is definitely not cut as deep,what do ou guys think of bridgestones where they wear on usually the outer edge about 1inch or so from he shoulder see them a lot on Nissan micros they are a right pain.
|
|
Daveg
NT & VTS Council member
I believe I am perfect, but others may differ in opinion?
Posts: 1,549
|
Post by Daveg on May 6, 2012 21:52:07 GMT
Both pics are the same make/type of tyre. The top pic has very little centre circumferencial (new word I think) tread left but as it's manufactured/designrd to wear out before the main full depth tread containing the TWI's then as long as any other full depth tread remaining in the centre 3/4's is not less than 1.6mm then it's a pass. The bottom pic is the same tyre but not done as many miles/worn down as much as top pic. I find problems arise from determining if the tread, particulary on the edges inside the centre 3/4's area doesnt meet the main tread if the tyre's getting worn as you can't see a "step" Also it's not easy to judge from 2d pics! But I think this is where your coming from is it Dave? Your right that is were I was coming from
|
|
Daveg
NT & VTS Council member
I believe I am perfect, but others may differ in opinion?
Posts: 1,549
|
Post by Daveg on May 6, 2012 21:57:29 GMT
I would pass and advise on the top pic centre tread doesn't appear to be cut as deep as other part of tread,where I work we have a certain brand of tyre and when brand new that centre band is definitely not cut as deep,what do ou guys think of bridgestones where they wear on usually the outer edge about 1inch or so from he shoulder see them a lot on Nissan micros they are a right pain. In regards to my first picture, if that make of tyre was the only one on the vehicle and you did not have another tyre same make for comparison, could you when presented with that tyre devoid of tread in the centre circumference really know whether the tyre had been over inflated, which would have the same effect? Suppose a VE retested it and decided that the tyre should fail? How would you convince the VE that you made the right decision? I am assuming that no second same make of tyre is available, and the VE thinks you made a clear wrong decision? How do you get round it and come out smelling of Roses? Dave
|
|
|
Post by drivewasher on May 6, 2012 23:36:38 GMT
you can see an actuall step
|
|
Stealth
Full Member
God made me do it !!
Posts: 79
|
Post by Stealth on May 8, 2012 8:02:20 GMT
Can't see how any VE with an ounce of common sense, and an understanding of test standards, would want to do that based on Pic 1
|
|
phaetonott
Nominated Tester
I may not be right but at least I am trying!
Posts: 376
|
Post by phaetonott on May 8, 2012 21:15:22 GMT
Can't see how any VE with an ounce of common sense, and an understanding of test standards, would want to do that based on Pic 1 BUT we are talking VOSA now stealth
|
|
phaetonott
Nominated Tester
I may not be right but at least I am trying!
Posts: 376
|
Post by phaetonott on May 8, 2012 21:18:19 GMT
Ignoring the centre groove, which I consider to not be a testable groove, I reckon the outside edges are getting mighty close to a fail. I can't make out any wear bars in the pic.
|
|
Daveg
NT & VTS Council member
I believe I am perfect, but others may differ in opinion?
Posts: 1,549
|
Post by Daveg on May 9, 2012 12:10:45 GMT
The pictures as far as I can see don't show any TWI's. I have also seen tyres designed in the centre like above where they are just solid rubber and no grooves manufactured in at all. It's late now but maybe I should have posted the first picture on its own and after replies then the second Is it possible on some manufacturers tyres to have a centre groove designed with more than 1.6mm, then the customer over inflates the tyres and they become devoid of tread like in picture 1 above? Is this area really cut and dried without the manufacturer blue prints? Dave
|
|
nitros44
Nominated Tester
esto es un negocio serio
Posts: 741
|
Post by nitros44 on May 9, 2012 22:54:36 GMT
I would say looking at example 1 to me it would be cut and dry ;but others may have different opinion Looking at the tread pattern in question and in reference to the main grooves that extend outward from the main central block;these grooves start from that location with a step down and appear to be the same depth towards the the shoulder,from what i can make out the tread remaining in the grooves would pass/advise. 1st impressions on looking at the tyre it would fail;however this is where a little more time and thought would have to be given before making the decision to pass,fail or advise. I would then be faced with a situation on weather or not the main block of rubber in the center of the tread ever had grooves which may have worn out and may of been cut as deep as the main grooves?;because now that central band has worn smooth and looks a fail,but is it!! If another tyre of the same spec is fitted to the vehicle then a comparison can be made,if not then a tester will have to make call based on the facts in front of him at the time of inspection using his experience and knowledge. To me it is clear just by studying the tread patten that the central band block,may of at some stage in its life contained shallow grooves which where never cut as deep as the main grooves nor designed to last until the tyre reached 1.6mm;in other words once the shallow groves had worn out all it left was part of the tread without grooves as it was designed to do But this is irrelevant now,if it did some indication of a groove would still be evident,in this example. What gives this away is the prominent step down from the central block on either side. If its a situation and its not clear which parts of the tread patten remain testable in borderline cases and element of doubt exists, would be to pass/advise in my opinion
|
|
phaetonott
Nominated Tester
I may not be right but at least I am trying!
Posts: 376
|
Post by phaetonott on May 14, 2012 21:13:54 GMT
Here's an interesting tyre The only place where the tread can be measured is the two straight grooves in the middle. The car had a brand new spare of the same make so I dipped the tread. The two central grooves measure 7.8mm, the remainder measures 6mm to 5.4mm at the edge. This tyre could wear completely smooth apart from the two grooves three quarters of an inch apart in the centre! As an MOT issue, imagine a tyre did come in with just the two grooves showing, you pass and advise. and then the car gets involved in an accident which the investigators put down to skidding on wet roads dut to smooth tyres. Attachments:
|
|
phaetonott
Nominated Tester
I may not be right but at least I am trying!
Posts: 376
|
Post by phaetonott on May 14, 2012 21:18:04 GMT
This one however has the word "STOP" moulded onto the top of the wear bar. Problem is.... once you actually reach the legal limit the word has worn away! I'm assuming that squiggle in the centre band is also some kind of wear indicator Attachments:
|
|
nitros44
Nominated Tester
esto es un negocio serio
Posts: 741
|
Post by nitros44 on May 19, 2012 20:56:57 GMT
Here's an interesting tyre The only place where the tread can be measured is the two straight grooves in the middle. The car had a brand new spare of the same make so I dipped the tread. The two central grooves measure 7.8mm, the remainder measures 6mm to 5.4mm at the edge. This tyre could wear completely smooth apart from the two grooves three quarters of an inch apart in the centre! As an MOT issue, imagine a tyre did come in with just the two grooves showing, you pass and advise. and then the car gets involved in an accident which the investigators put down to skidding on wet roads dut to smooth tyres. I would have to disagree with the bottom statement,if a vehicle was presented with a tyre(s) as pictured ;in a condition where only the 2 grooves remained then the tyre pictured would fail. ;D To the right of the picture they is a tread wear indicator evident in one of the horizontal grooves,not as prominent as the tread wear indicator in the vertical center groove is,but it is still a tread wear indicator. ;D I can see how the tread pattern has grooves that start from the center that have slants pointing to the outer shoulder which would not be testable but the rest of the groove is.I don't believe the tyre has stepped wear contained in the tread pattern and there may be some variation within the tread pattern with regards to tread depth when tyres are new as stated,but if the grooves on this tyre have a variation regards depth but still has tread wear indicators,then the 1.6mm 3/4 rule apples to those grooves. This small variation in tread depth from new; i believe will even itself out over time and may not be an issue by the time the tyre is due to be changed(excluding stepped wear etc) If once again a NT was faced with a tyre in a condition as stated a NT would be looking for the minimum requirement once the central 3/4 was established and without the benefit of another tyre to compare one with the other or a new spare to determine what grooves are at what depth,the NT will have to work out himself which sections of the tread pattern are indeed testable. If i was faced with the tyre pictured with just the 2 central grooves evident and totally smooth either side as far as the end of the tread pattern then i would have to fail it based on fact at the time of test that 1.6 should be evident to some degree within part of the horizontal grooves. I have seen these tyres before and are not easy to work out when worn and can see what pheatonott is saying Attachments:
|
|
phaetonott
Nominated Tester
I may not be right but at least I am trying!
Posts: 376
|
Post by phaetonott on May 19, 2012 21:07:29 GMT
Sorry Nitros, there are NO wearbars anywhere except the two in the central grooves. The deepest tread outside the central 2 grooves is 6 mm, it can wear away before any wearbars reach the surface
|
|
nitros44
Nominated Tester
esto es un negocio serio
Posts: 741
|
Post by nitros44 on May 19, 2012 21:33:45 GMT
What has to taken into consideration here is just because a groove does not have a twi contained within the groove does not mean it is not testable
|
|